I noticed today that I have 300 Facebook "friends." Before moving, I sat at a comfortable 250 for a long time. I've always been pretty nuts about turning down friend requests, because I post a lot of photos and stuff that I frankly don't want people to see unless I know them. Since moving, obviously I've got new folks from work (though my policy is never add friends up or down your reporting line), and I've finally got family starting to come on board. Shit, even my mom is on Facebook now, though only so she could see photos of her grandson.
For all of the hysteria and nonsense about privacy, I'm pretty happy with the way Facebook keeps things limited.