I never liked the look of Myspace pages. Since there is a stigma about adult men there being viewed as pedophiles, I never joined up there.
I'm using Facebook for friends and family and LinkedIn for professional contacts.
The average age of Facebook users has increased a lot in the last few months. I've been amazed how many of my high school and college classmates are popping up on it who weren't there last fall. Here are a couple of recent articles discussing the trend.