For a man who "marshaled the power of the Internet unlike any candidate before him," said Domenico Montanaro in MSNBC, Barack Obama is rough on Facebook. During a back-to-school event on the day of Obama's big speech to young students, he warned children who dream of becoming president to be careful what they post on the social-networking site (watch Obama's Facebook warning), because their photos and comments could come back to haunt them. It's sound advice, because things live forever on the Web—as ex-green-jobs czar Van Jones learned after anti-Republican comments he made in a YouTube video helped force his resignation.

Well, yes, but Van Jones was a special case, said Gateway Pundit. His troubles can't be chalked up to Facebook. Kids, if you want to avoid Jones' fate, "avoid communist rallies," and, whatever you do, don't sign any 9/11 Truther petitions.

President Obama was just telling kids something they should already know, said Adam Ostrow in Mashable. Research shows that nearly half of companies screen social media profiles in the hiring process, and scratch applicants who post provocative photos or bad-mouth former bosses. And aspiring politicians have even more reason to exercise "extreme caution," because everything they post could some day give cable news channels "fodder to opine about."