I used Facebook a lot when I was on maternity leave last year. Since moving and going back to work and having the computer in the dingy basement, I haven't really been on it. I found it was fun when you have the time and you get to catch up with a lot of people you haven't seen forever, but it can become a little stalker-ish.
I'm not really concerned about the privacy aspect of facebook, because I don't post anything I would worry about anyone seeing and if I don't know someone I don't accept their friend request.
I'll probably keep using Facebook after Betty Blogger, but I have such a hard time uploading pictures at home, I don't know how up-to-date it'll be.