Eh... I don't know. I think there is actually a disadvantage to everyone being on the network. I left facebook when both my mother and my stepmother joined. I don't think I'm alone in this need to compartmentalize my personal life in ways that facebook doesn't support.

Now, my professional life, well, I'm on linkedin, and I like it quite a lot. But facebook has lost it's compartmentalization, and I think that's bad. It used to be just for college kids, which is a great niche, everyone else wants to be in the same place as the cool college kids. But if mom starts showing up at the local watering hole, I think the kids are going to find a new place to hang out.

The thing about linkedin is that yeah, I want to compartmentalize my professional life to some extent... but it's one way compartmentalization. I mean, while I don't really want all of my personal life to bleed into my professional life, I mean, my business partners and customers don't need to read about my relationship problems. Not that I'm ashamed of my personal life or anything; it's just unprofessional, and I think impolite to shove that in their faces. But the other way around is fine; I'm okay with casual friends reading up on what I do at work.

Really, the compartmentalization of my private life is very complex, and I'm not a very private person.

Just my opinion; I'm clearly not an expert at this sort of thing.

I'm in my 30s. My social group is mainly urban and mobile. It certainly seemed that vast majority of people around my age were on MySpace, and I say this as someone who never actually joined it with a real account. Incidentally, the same people who used MySpace heavily are the ones whose posts fill up my Facebook wall. In fact, most of those people were also on friendster.