I'd say different (slightly) I do like the time line idea and the in-line conversations. With lots of friends twitter is impossible to use.

I can click "view responses" and see everyone talking to me, which means I can reply, which means the value is higher (for me) than twiiter

that's probably not the case for everyone, but it helps me

replies, confusing timeline, choas, emoticons, facebook/myspace popularity, karma, (non of the above)

oh yeah, if you have good karma, you can get more smileys LoL