Cyrus, like any other girl, is negotiating that murky era between childhood and womanhood – she just gets to do it in front of the world. Being sexual is part of being 16, even for America’s sweetheart. But though Cyrus did indeed strut around and, at one point, dip it down low, the more salacious moment came earlier in the song, when she shimmied with a quartet of aggressively rump shaking would-be Scores girls. Cyrus, for her part, told MTV before the show that her performance was intended to represent her southern roots and “being so proud of where I’m from.”

With her powerful voice, classic beauty, and billions in sales, she’s probably figured out she doesn’t have to trade exclusively on hoochie to get ahead. As she matures, she’ll likely be able to hang on to her younger “Hannah Montana” fans while she vies for the attention of a new audience of masturbation enthusiasts.

As the mother of two girls myself, I generally try to avoid knee jerk “what about the chiiiiiiiiiildren?” horror. And I firmly believe the only person whose job it is to be their role model is me. Nevertheless, there is something undeniably dispiriting about watching a young woman whose songs celebrate intelligence and ambition shaking her ass like any other prefab Pussycat Doll. What makes Cyrus’s performance depressing isn’t that it’s shocking; it’s that it's so fucking familiar. It’s that homogenization of eroticism, the way that the gentleman’s club is the template for so much of what passes for entertainment from a female, that’s such a bummer. It’s the choreographic crutch of Britney. Beyonce. Fergie. Rihanna. It’s not enough to have looks and talent, whatever your age, you should probably also dress and move like you carry your wages in your thong.

When my 9-year-old daughter watched the clip today, she was underwhelmed, declaring the dancing “just okay.” She had no judgment, and I didn’t suggest one. She did however ask me why her idol was dancing in her underpants. Cyrus herself is likely equally unruffled. Right on schedule, “Party in the USA” debuted yesterday in the Billboard Top 40.

Cyrus is just 16, around the age of the characters she's playing, and the show, like the movie, is targeted to girls who are much younger. (Yes, some boys may like it too, but for convenience' sake, I'm going to stick with the female pronoun.) The concept, at its core, is simple and brilliant. Cyrus' regular-girl character, Miley Stewart, has always dreamed of being a singer, but she also wants to have a normal teenage life. So she strikes a deal with her father, Robby Ray (played by Cyrus' real-life dad, Billy Ray): As her sunny, somewhat baby-faced brunette self, she'll go to school and do regular teenage stuff. But she also has the freedom to don the aforementioned blond wig and perform in the guise of Hannah Montana; only her family and her closest friend (played by Emily Osment) know her secret. That way, as she puts it in one of her chirpy, cheerful songs, she gets to live in the best of both worlds. As Hannah Montana she temporarily ceases to be a sheltered little girl and instead becomes a free agent, a performer who gets to try on the clothes, and the persona, of an adult sexual being.

Whether or not you think this idea is harmful for kids is up to you, but I very clearly remember being 6 years old and believing that someday I'd grow up to be either Emma Peel or Honey West, the character played by Ann Francis in the short-lived '60s TV show of the same name. (She was a private detective who wore black leotards and kept a pet ocelot in her bachelor-girl apartment.) I can assure you that, much to my disappointment, I grew up to be neither, but at least I now understand what the fantasy was about: It allowed me to try on the idea of being a glamorous, sexy adult without having to deal with the attendant responsibilities and complexities. I could always return to the safety of being a kid, which is the central notion behind "Hannah Montana."

The double-identity concept is laid out very clearly in "Hannah Montana: The Movie," so even if you have an Amish child who's never seen television, you can be assured she'll understand the movie's logic perfectly. (Why you'd be bringing such a child to the movies in the first place is between you and the elders.) Those of you who will be dragged to the theater this weekend might want to know that the plot of "Hannah Montana: The Movie" is slender but serviceable: Robby Ray believes Miley is becoming too wrapped up in the whole Hannah Montana thing, and wants her to forgo an important engagement to attend the birthday party of her grandmother (played by the wonderful actress Margo Martindale) in Tennessee. Miley doesn't want to comply, but she's tricked into it. The good news is that a former grammar-schoolmate of hers, Travis Brody (Lucas Hill), has grown up to look like a Bruce Weber model, complete with cowboy hat and artfully fitted-but-worn-in plaid shirt, and now works on her grandmother's farm.

Assorted conflicts and adventures ensue, and the movie overall is painless if not exactly electrifying. (The director is Peter Chelsom, the English filmmaker and actor who has previously made some very entertaining films for grown-ups, including the 2001 romantic comedy "Serendipity" and the 1991 charmer "Hear My Song." The script is by Daniel Berendsen, based on characters created by Michael Poryes, Richard Correll and Barry O'Brien.) Miley Cyrus, as Miley Stewart, is appealing enough, albeit in a too-cute way. She simply needs to fill the expectations of her millions of pint-size fans, which she does with exacting professionalism.

And it's not her fault that as Hannah, she has that trying-too-hard look. Maybe it's the movie's makeup artists who failed her -- as Hannah, she just doesn't look fresh and dewy enough, as even a teenage pop star ought to. And the wig looks a little too much like something Flip Wilson might wear as his own alter ego, Geraldine.

Worst of all for Cyrus, Taylor Swift -- not just a kiddie sensation but an exceptionally talented singer-songwriter -- makes a brief appearance in the movie as herself. Swift is a cool, composed performer, but she also comes off as genuine, while Cyrus is merely gen-u-eyn. In her very small cameo, Swift unintentionally but definitively upstages poor Hannah Montana. Little girls won't notice that now, but someday when they're older, and having a second look, they'll make the distinction. For now, they just need to worry about being little girls, and that's plenty.

And so we have arrived at Zac Efron's moment. In this month's Interview magazine, the well-scrubbed 21-year-old star of "High School Musical" loosens the shackles of his pukka-shell necklace and undergoes a dirty-sexy makeover -- black-and-white photos feature him rolling in the mud with a naked model (Lithuanian Edita Vilkeviciute), her pert nipples visible, and looking like he is 15 years late to Chris Isaak's "Wicked Game" video shoot. The whole package is a self-conscious attempt to rescue Efron from the sea of Disney banality in which he has been dog-paddling for some time: The artsy cover ominously declares, "Zac Efron Is the Future." The interview is conducted by beloved indie director Gus Van Sant -- a man whose stamp of approval is so coveted by young Hollywood that it became a plotline in HBO's "Entourage" -- and the pair gab about vintage furniture and Efron's upcoming period film with Richard Linklater, "Me and Orson Welles." The repeated message here is that you won't have Zac Efron to sing your four-part harmonies anymore. On Tuesday came the announcement that Efron had pulled out of his starring role in the remake of "Footloose," a part that seemed to seal his fate as a song-and-dance plaything for tween America and the next logical step in his retread of vapid '80s teen idoldom. Ditching that part is possibly the most interesting thing Efron has done in his career -- which is, admittedly, a short list, including the time he told Elle magazine that his mom bought him an economy box of condoms. 

Even in the pantheon of bland teen stars, Efron always seemed particularly animatronic. (That's not even his real voice in the original "High School Musical," though he insisted on singing in the sequels.) With his '50s-era Boy Scout good looks, annoyingly windswept bangs, and the made-for-the-tabloids romance with Vanessa Hudgens, Efron has never been much more than a punching bag for those of us over 10 years old. When Rolling Stone declared him the "New American Heartthrob" in 2007, it seemed to be saying more about its own desperate bid for relevance than anything else. "As long as I stay boring, I think I'll be fine," Efron said in the cover story. And there did not seem to be any danger of him doing otherwise. Which is another reason why this moment is exciting: He could have sucked on the bong of "HSM" for years, living a cozy existence fortified by Teen Choice awards, in which the most serious question he faced was whether or not he liked to wear makeup. 

I don't mean to suggest that by splattering mud on his face and pressing his pecs against a naked lady, Efron will suddenly morph into Johnny Depp. Depp displayed hints of his talent even in his earliest roles, whereas Efron's chops have yet to manifest. In fact, it's a bit squirm-inducing to hear about Efron's artistic aspirations, however fledgling and undefined they are. "I'm getting a list of great films on my iPhone," he told Gus Van Sant, "and every time somebody mentions one, I try to go out and watch it." (He just saw "Ordinary People." Verdict? "I was amazed.") His next film is "17 Again," a hokey-sounding age-inversion film in which he plays a 37-year-old stuck in the body of a teenager, which is not likely to land him on anyone's Oscar shortlist.

Nevertheless, there's something invigorating about a teen idol attempting to wriggle free of his constraints. It's a gamble for a star whose fame relies on the conflicted desires of the young girls (and boys) who adore him, in part, for his androgyny, because he is unthreatening, sweet and cuddly as a puppy. No matter how sexualized our culture becomes, the overwhelming success of "High School Musical" -- in fact, of every teen idol -- confirms that kids crave the soft-focus fantasy of romance and sexuality while keeping all the dirty, nasty stuff at arm's length. (Hello, Jonas Brothers.) Trying to transition into a more grown-up role is the sword on which so many beloved teen idols have fallen. But whether he can pull a Depp or a Timberlake, or whether he winds up as the next David Cassidy, forever plagued by the credibility that eluded him, Efron's career now has a quality it has lacked for so long: It has become unpredictable.

 Teen idols who have crossed over

The career span of a dreamy pinup is often painfully short, but a handful have cheated fate and turned themselves from punch line to marquee player.  Here are a few hits (and near-misses):

Johnny Depp

Almost as soon as Depp pierced public consciousness as the young star of late '80s teen-cop drama "21 Jump Street," he made it clear he wasn't a going to be a garden-variety idol. He started talking in interviews about making a movie of Kerouac's "On the Road" and threatening to shave off his hair. By 1990 he was fleeing his prime-time trap for a starring role in John Waters' "Crybaby," which he described at the time as "the ultimate juvenile-delinquent musical comedy" -- soon to be followed by Tim Burton's "Edward Scissorhands," the first of many quirky movies he would choose on his way to becoming one of the world's most admired actors.

Justin Timberlake

From his early appearance on "Star Search" to his squeaky-clean image in 'N Sync, there was little to suggest towheaded Timberlake was anything more than harmless fantasy fodder. He and Britney were the reigning fairy tale couple -- but in 2003, they broke up and in one fell swoop, both young lovers tumbled into adulthood. Timberlake took up with the very grown-up Cameron Diaz, and his debut album catapulted him to superstardom. He became a regular Rolling Stone cover boy, made even more infamous for exposing Janet Jackson's nipple during the Super Bowl.  But he found respect and widespread critical acclaim with his adventurous album "FutureSex/LoveSound." Timberlake had pulled off the ultimate former teen-pinup feat: building up artistic credibility while keeping the fans panting.

Britney Spears

The beleagured pop star has zigzagged across the line of credibility so many times that it's hard to remember when she first arrived. La Spears was incubated in "The New Mickey Mouse Club," of course, and burst on to the pop scene with an album that had one bona fide megahit ("Baby One More Time") and a lot of cloying nonsense. She had all the trappings of a one-hit wonder, but Spears leveraged her time in the spotlight with a series of then-shocking magazine spreads, beginning with David LaChapelle's Rolling Stone cover in 1999, flaunting her sizzling teen bod while promising to keep her virginity tucked away in a heart-shaped box. It was all a bunch of calculated nonsense, of course, but it worked, along with all those perfect Max Martin pop confections, so that by the time she swapped saliva with Madonna on the MTV Video Music Awards in 2003, the homespun Louisiana teenybopper had transformed herself into the country's reigning pop princess. And then, other things happened. Maybe you heard.

Bobby Brown

Booted out of the '80s teen group New Edition for bad behavior, Bobby Brown could have easily been a footnote to the '80s boy band era -- and a minor one at that. His first solo attempt was largely ignored, but his 1988 smash album "Don't Be Cruel" was all swagger and sass, and the hit "My Prerogative" became an anthem for teen-idol rebellion when Britney Spears remade it in 2004. Brown became a blueprint for Spears in another way, as his music career soon became eclipsed by the hot mess of his tumultuous reality-show life.

Mark Wahlberg

A life of crime or life in a boy band seemed to be the two options facing Mark Wahlberg at the age of 13. He switched off between the two, spending a short stint in his brother Donnie's band New Kids on the Block and another in jail before finding fame as Marky Mark and the Funky Bunch. The party jam "Good Vibrations" was a massive hit, as was the video in which Wahlberg flexed his bare, extremely buff chest. His career as a Calvin Klein underwear model eventually overshadowed his music, and a dead-end future as a hunky has-been was looming. But in 1993, Wahlberg got a part in a movie, which led to a string of strong performances in movies like "The Basketball Diaries" and "Boogie Nights." Nowadays, Wahlberg not only acts (nabbing an Oscar nomination for "The Departed" in 2006) but he's also a Hollywood exec, producing the HBO series "Entourage" (loosely based on his own experiences) and "In Treatment" -- about as impressive an outcome as a pretty boy teen idol could imagine.

Miley Cyrus

Last April, tween superstar Miley Cyrus, aka Hannah Montana, tried her hand at a different kind of girl power: posing for a racy Annie Leibovitz portrait (just as David Cassidy had once done), draped in nothing but a bedsheet for the cover of Vanity Fair. What was presumably meant to signal a break from the goofy girldom of her Disney career prompted a ferocious backlash among parents and Disney itself, panicked that it might be losing its prized pony. A contagion of apologies and hand-wringing trend pieces later, the moment still stands as a transition for Cyrus, who managed to catapult herself into the national conversation, though she's back in line now for the most part, starring in April in another soft-focus "Hannah Montana" film. More moments of teen rebellion inevitably await.

 David Cassidy

OK, so David Cassidy never exactly crossed over to mainstream credibility. But it's not like he didn't try. Before he was cast as Keith Partridge in 1970, Cassidy had dreams of being a serious actor and musician -- but his massive TV superstardom derailed his plans and left him with a trail of screaming girls and a zillion lunchboxes bearing his image. ''I was playing a part on television, and that became the David Cassidy story. But underneath, there was this guy who was dying to do 'Purple Haze,''' he once told Entertainment Weekly. He desperately tried to shred his image by posing for a nude Annie Leibovitz Rolling Stone cover, his pubic hair on show, and dissing "The Partridge Family," but to no avail. Cassidy didn't find a place for himself until 1983, when he took the lead role on Broadway in "Joseph and the Amazing Technicolor Dreamcoat," a musical that has become a refuge for many former teen idols (Donny Osmond, Andy Gibb, Michael Damian and Leif Garrett among them) seeking salvation.

-- Joy Press and Sarah Hepola 

 

Then I saw the photos. Huh. Am I supposed to be outraged? I'm not. You can see more skin at a prom. I too cringe at the way girls are sexualized earlier these days -- and I've been known to throw fits about those sleazy American Apparel ads -- but I actually tend to agree with Leibovitz, who said in a statement that it's "a simple, classic portrait, shot with very little makeup."

But outrage is certainly out there for the taking right now. You can't get much more G-rated (or popular) than Hannah Montana, and parents are busy finger-wagging for the way she has failed her fans. Gawker rails on Leibovitz for being a controversy-baiting hack (which she kind of is): "We're hardly the type to play scolds for risque media attention-getting stunts," it writes. "But there is such a thing as a bright line that you simply don't cross."

But as far as I can see, the bigger problem is the other photos of Miley Cyrus, ones that surfaced last week. Now those aren't simple or classic. As one friend recently theorized, Cyrus may be backpedaling on the Vanity Fair shoot just to deflect attention from being another stupid teen with a cellphone camera.