Less than a month after the world watched Tunisia celebrate the collapse of the country's strong-arm ruler, the scenes in central Cairo on Friday offered an even more potent display of the newfound power of the Arab street: fist-pumping crowds cheering the end of President Hosni Mubarak.
The downfall of Mubarak -- one of the mainstays of Middle East politics and Western policies in the region for nearly three decades -- marks another history-shaping moment for the Arab world from a country seen by many as its political and cultural crucible.
What began as a tentative cry against an entrenched regime in late January grew into a popular mutiny that forced Mubarak to flee Cairo and then step down in just a few dizzying hours.
But the revolution on the Nile -- which reached its climax 32 years to the day after the fall of the government of the U.S.-backed shah of Iran -- raises deep questions about the long-term stability of other Western-allied regimes across the region and could significantly recalibrate America's policy playbook from the Mediterranean to the Gulf.
There is no guarantee that the reform wave will wash over another country soon. An attempt to stir Egypt-inspired protests in Syria earlier this month was snuffed out by security forces.
The reverberations, however, are already being felt in smaller but significant ways.
In Saudi Arabia -- the other traditional cornerstone of U.S. interests in the Mideast -- a group of opposition activists said Thursday they asked the nation's king for the right to form a political party in a rare challenge to the absolute power of the ruling dynasty.
"You know well that big political developments and attention to freedom and human rights is currently happening in the Islamic world," the activist said in a letter to King Abdullah, who was one of Mubarak's staunchest supporters up until the end.
Jordan's new prime minister, Marouf Bakhit, promised Wednesday to continue political reforms demanded by protesters who forced King Abdullah II to reshuffle the cabinet. Last week, Yemen's President Ali Abdullah Saleh -- a key U.S. ally in office for more than three decades -- bowed to pressure from protesters and announced he would not seek re-election in 2013 and would not try to pass power to his son.
"Egypt is going to have a big, big impact around the region," said Salman Sheik, director of The Brookings Doha Center in Qatar. "It is -- as it always has been -- a bellwether for what happens elsewhere. It's wrong, though, to get into a count about what country could be next. The real impact is already being seen in reforms that are coming from countries feeling the pressure."
It could hit next in the strategic Gulf kingdom of Bahrain, where opposition groups are calling for street rallies Monday.
Bahrain is home to the U.S. Navy's 5th Fleet and the most politically divided in the Gulf. Majority Shiites have long alleged they face second-class status under the Sunni rulers. Last summer, the tiny nation was torn by clashes and riots after a wave of arrests against perceived Shiite dissidents.
On Friday -- just hours before Mubarak stepped down -- Bahrain's King Hamad bin Isa Al Khalifa granted each Bahraini family the equivalent of nearly $2,700 in an apparent bid to calm tensions.
In Kuwait, the other Gulf nation with serious political opposition, outlawed any "gatherings, rallies or marches" after Friday prayers, said a report on the state news agency KUNA.
"Everybody should put the interests of the homeland above all considerations," said the statement by Kuwait, which has key U.S. military bases and is an important way station for the U.S. military withdrawal from Iraq.
It also showed how close any unrest in the region comes to U.S. military and political bulwarks -- seen as a critical front-line alignment against Iran.
But even Iran's main Mideast ally, Syria, has been showing some concessions to the reformist fervor. This week, Facebook and YouTube were available for the first time in three years amid signs Damascus may be lifting its ban on the popular social networking websites that have helped energize and organize protests.
Speaking in Michigan on Thursday, U.S. President Barack Obama said the world is "witnessing history unfold" in Egypt. But he also was quick to extend a hand of friendship to the "new generation" who led the uprising, which includes the well-organized Muslim Brotherhood group that could steer the new leadership in Egypt away from its tight bonds with Washington.
"The U.S. is being forced to rewrite its Middle East diplomatic strategy on the fly," said Sami Alfaraj, director of the Kuwait Center for Strategic Studies. "But everyone is in the same position to some extent. The events have been so unexpected and so fast."
Tunisia offers a cautionary tale for what could be ahead in Egypt or elsewhere.
Tunisia's interim President Fouad Mebazaa was given decree-making powers this week to speed reforms and try to quell lingering unrest following the ouster of former dictator Zine El Abidine Ben Ali on Jan. 14.
But a prominent Tunisian dissident told The Associated Press in Paris that he worries the "people's revolution" is at risk of collapsing into chaos and possibly leading to calls for the return of the deposed president.
"All this is extremely dangerous for the country," said Moncef Marzouki.
Just seconds after Mubarak's departure, the new tools of political activism -- Facebook and Twitter -- were buzzing with encouragement to maintain the momentum for change across the Middle East.
A Twitter message from Egypt played on the digital lingo: "Uninstalling dictator, 99 percent complete."
Another -- perhaps inadvertently -- appeared to carry a message for the rest of the region as he joined the avalanche of posts about Mubarak.
"Dude, Egyptians invented writing on the wall," it said. "You really should learn to read it."
Murphy, the AP's bureau chief in Dubai, has covered Middle East affairs for more than a decade.