Gen Y just doesn't care about their privacy.
Speaking as one of them, I am not worried about the information that goes up on my social networking profiles. I share personal information every day and tagged in photos every Monday morning after a big weekend. And there are some shocking ones.
The reason I bring this up is because Gen X's are constantly telling me that this is going to affect my career with employers frowning upon such behaviour. But I disagree. Sooner or later employers are going to release that the high majority of Gen Y have at least one Facebook photo that shows them partying, drinking or worse. Interestingly, I don't have a problem with complete transparency or the need to hide what I do in my own time.
What's going to be really interesting is when Gen Y takes a majority in the workplace and they (we) become the employers of the next generation, what ever they're called. Can you even imagine what the social norms will be then?
I actually have a link to my Facebook page in my email signature. And I send emails to potential future employers every day. I'm not worried about the photos they will see. Although sooner or later someone might realise I only have one suit and two shirts that I have to keep alternating....