Romney triggered a Twitter-storm after he attacked PBS with his now-infamous comment. PBS shot right back, though, releasing a statement that went viral. PBS also leveraged the Twitter meme (Big Bird was trending most of the day), by displaying an ad every time someone searches for "Big Bird."
The ad read “PBS is trusted, valued and essential," and linked to a site that shows the real impact (and affordability) of PBS. Judging by its reach, it seems like someone at PBS could teach the Romney campaign about social media.