Twitter has been around for quite some time now - I reported on it a while back.
It seems that twitter is on the move - I see a lot of twitter activity on blogs, for some reason it seems to be more popular than ever before. But if I look at the features, nothing's changed. It's still the same thing. It has even cought the attention of the Wall Street Journal, which tells Kera Richard's story :

Kera Richard has recently become obsessed with a new online tool for connecting with friends. For the past three weeks, she has joined the crowds on Twitter.com, a site that invites everyone to answer the question: "What are you doing?"

According to the paper, twitter has received some attention from important people, presidential candidate John Edwards.
Personally I think twitter is fun, but I can't see a real use for it yet. Besides that, I would like to see RSS feeds tied to twitter. The current badges don't give you much history, and that's what could be interesting.