I love our social networks for the very reasons lulu put out above. However, i don't want my public real life identity to associate with my private internet identity, simply because I can be myself on the internet. The consequences in this judgemental town of saying what I really think would probably be Shunning.
Not that certain people don't shun me already, of course. But I just have to live with it.
The only thing that really worries me is a repeat of that scary-stalker event we had a year or so ago -- but now, with workplace, home and private contact details involved. That's my main (if somewhat paranoid) concern. I'm thinking of a second account to like abandonia from, with a cartoon avatar, for that very reason.