About the "No one forces anyone to sign up for Facebook", well... You now tell me that all that exclusive promotions/giveaways that are on Facebook doesn't force you to sign up? Today, there is no giveaway if you're not on Twitter or Facebook.
At least, Twitter doesn't require as much personal data and doesn't link you to that forgotten high school guy you went to school with in 1967 (I must admit, that scare the crap out of me).
I don't have a facebook account, and only a forgotten Twitter account (that i used for a college work). I had that Orkut once, but... Well, i'm not into social networks (except the ones you PRIVATELY chat with other people, like MSN/XFire/Skype without lending a handful of personal data which is visible to the whole wide world).
I hope FB goes down in flames, to be honest. So I can participate in giveaways again =P.