This is all the rage right now! Micro-blog meets real-time chat.
The community is great, the developers aren't strangers and actually speak to you, new features seem to be implemented everyday. Guests can even reply to your "shouts", as they are called, without being required to have an account.
The full information on Rejaw's features can be found
here
You can find me at Rejaw (
Rejaw: Andrew Trinh) too.