Twibble is a mobile client for Twitter. It works on most (if not all) Java enabled smartphones including Nokia, Blackberry, and Sony Ericsson.
It has all of the standard features from a twitter client including:
- posting tweets via wifi, gprs, sms
- auto refresh
- send photos to twitpic (new beta version uploads to Mobypicture.com
- re-tweet (forward) of tweets
You can get the current version here and information on the beta is here here
It is (so far) the best free twitter client for my N95. There are other alternatives that are a bit more polished but they are not free, and twibble still seems to be the best. The beta version adds support for showing avatars and uses less memory (amongst other things).
Go check it out!