Those of us that have been watching how people use public networks (I started in 1982) know that there is a certain "newbie" phenomenon that takes place when some new feature or service is introduced. I have always been skeptical of the "social networking" trend, which is best represented by sites like FaceBook and MySpace.
As James Lileks has noted, the notion that it is "cool" to post pictures of ourselves in compromising situations is a new and somewhat baffling concept to anyone who has worked for more than a few years. But today's college students have somehow decided putting pictures of themselves doing profane or illegal things is cute/funny/cool.
But we may have reached the tipping point as the MySpace and FaceBook newbies begin to see that actions have consequences. The University of Minnesota has kicked several players off the football team for posting pictures online that do not meet the team standards of conduct. And as more and more reports surface of employers rejecting job applicants who have posted inappropriate material online, the somewhat juvenile appeal of exposing one's self (literally) online is going to diminish.