Walter Kirn thinks that the the combination of Americans' natural exhibitionism and the Internet is killing privacy. I'm not sure if the behaviour he describes isn't just a passing phase as the world adjusts to "social" web sites and their ilk. Once the teenagers and undergraduates gratuitously flaunting the most private aspects of their lives online start to experience some of the consequences during their adult lives, they might start to care slightly more about their privacy.
Ed Felten had some interesting thoughts on this recently. Just like him, you might have noticed that I do not reveal a huge amount of personal information on this blog beyond my political opinions. I don't intend to start any time soon.