I’ve been using Gwibber on and off for a while now, but recently I’ve started using Ubuntu 10.04 full time and Gwibber has now been directly integrated.
Back when I used Gwibber before, it was a half-developed Twitter client. Its much more than that now and its progressing nicely!
Gwibber 2.29.90.1
Some people might compare it to TweetDeck for Windows, but it has a little ways to go before its as feature complete as TweetDeck.
I’ve decided to start making contributions to the client via user interface improvements and improving service reliability among other things. However, I’ve started with a simple contribution that is one requirement for me…the use of my favorite url shortener service: U.NU
U.NU is your basic url shortening service, but it lacks a great deal of features that other services typically offer such as detailed statistics for each link. This doesn’t bother me, as the most important thing to me is a short url. 
Now that I’ve submitted a (very) simple python script that enables a new url service in Gwibber, I’ve marked a point where I’ve actively began contributing to the open source community (to applications that are not my own).
Gwibber is now a part of Gnome so I’m hoping that when Gwibber 2.30 is released, along side Gnome 2.30, they will include my little patch/contribution so I can use my favorite url shortener in my tweets. This is the beauty of open source. 
If you’re curious about the theme I’m using, it’s the Homosapien Metacity theme. I used the online Homosapien Metacity Customizer to get the blue theme though. You can make your own remix of this theme there if you wish or you can just download the exact one that I’m using.