So, I've been using twitter sporadically. I'm still feeling it out and not sure if I will continue using it, but signs point to yes. For now.
It's like a weird form of irc-like chat in slowmotion, where you start off ignoring everyone in one gigantic world-wide room. Everyone is also ignoring you. You can befriend somene, which means you have essentially unignored them and now receive their messages. They're not seeing yours, though, until they befriend (or "follow") you.
You can also see who someone is following, but not who is following them.
I'm r3v there.
Also, for a complete waste of time, check out the mesmerizing Twittervision.