TwimGo is a Twitter client for Maemo, Symbian and MeeGo devices. It containes all the basic functionality like home, mentions, favourites etc. timelines, search, lists, trends. You can also easily open links and search mentioned hashtags. TwitPic and yFrog photo preview is shown in tweet details.
Downloads for N900 / Symbian^3 and Symbian S60v5.0 are available from the Twimgo Project page