I'm really enjoying Facebook. I think it might be most interesting for itinerant types like me -- I've moved a LOT and have good friends from each place I've lived, and it's so nice to get back in touch and hang out with them the way Facebook allows. (I also "hang out" with people who live here though -- recently ran into a friend and we noted that lately we've talked to each other more on Facebook than in real life !)
I definitely am not going for numbers, I've turned down or haven't responded to many friend requests.
That includes A2K people btw -- I've decided I want to maintain a bright shining line, worlds collide and all that, so if you're one of the people who sent me a friend invitation and I haven't responded, it's not personal! I might start a separate sozobe (or something similar) Facebook account though because it sounds like a lot is going on there amongst A2K'ers...