We teens are paradoxical creatures. We like private little circles, but in those circles we strut as much as possible.<p>A teen wants to be seen and noticed by all the right people. Sometimes that's friends, sometimes it's crushes. They need to control that audience, so that the wrong people don't see things, and so that they know how best to talk to people. Think of it like the cliques in school.<p>Facebook gives me people I know. MySpace gives me people I know. When I talk, I'm talking to people that I have a relationship with. That means I can talk differently, talk more directly and more emphatically. On Twitter anybody can listen, and that's a bad thing.<p>(It's still a bad comparison, though. Facebook creates a network with photos and videos and conversations and statuses and messages. Twitter only has statuses. The biggest draw of Facebook is its extensive, localized feature set.)
I think a large part in that teens already have strong texting networks.<p>One of the reason twitter works is because subscribe-and-publish communication has low transaction costs per message.<p>Teens engage in signaling behavior that has the high transaction costs of communication as an element of "conspicuous consumption".<p>I have totally no data to back this up, but research into this area is one of my interests, and am looking forward to performing some in the future and seeing if my conjectures hold up.