TwimGo is a popular Twitter client by Tommi Luakkanen (@tlaukkanen) for the Nokia N900 and has also recently become available for Symbian based devices via the Ovi Store. In its current iteration it is written in Web Runtime, but the upcoming version 2.5 has been rewritten with Qt Quick or more specifically Qt QML.
The end result is that the app now has a pretty snazzy UI, complete with all the bells and whistles that is no slouch when it comes to performance. Here is the video courtesy @mwkn:
The new version is not available for download just yet, but you can follow the developer for the latest @tlaukkanen. This version of TwimGo should also come to Symbian based devices once Qt 4.7 rolls out.