Again - I'll give a contrarian opinion...
I'm in the ~0.1% of Americans between 18-35 who do not have a Facebook account. I've been periodically bombarded with statements like "it's so hard to get ahold of you [because you aren't on Facebook]" or "you didn't hear about the party? I posted it on Facebook." My fiancée, brother, sister, and essentially all of my friends are on Facebook
Some conclusions I've drawn:
1) people who *actually* want to get ahold of me still manage to do so via email, phone, or in person.
2) from the "outside-looking-in" it does seem to be a phenominal waste of time.
3) Facebook has had a very poor record of protecting the hoards of data they mine from each of its customers. To some this isn't an issue, but to me it is. On three seperate occasions so far they've been warned by the DOJ.
4) A lot of social "drama' seems to start with "OMG, I can't believe she posted that!..."
I still seem to function in society, I still have friends (who are all on facebook) and I don't feel like I'm really missing out.