We've been using CEGUI for some time, I think the first version of CEGUI we used was 0.1.0. It's been really nice to see how the library matured and gained features, while at the same time retaining its speed and clarity, both in the code and the documentation. It's been a real pleasure to work with throughout.
We use a modified WindowsLook theme, with almost all GUI code written in Lua.
The main site of the client can be found here.
Here are some screen shots:
![Image](http://amber.worldforge.org/ember/screenshots/tn/screenshot_20071019_003835.jpg)
![Image](http://amber.worldforge.org/ember/screenshots/tn/screenshot_20071018_005635.jpg)
![Image](http://amber.worldforge.org/ember/screenshots/tn/screenshot_20071011_234148.jpg)
![Image](http://amber.worldforge.org/ember/screenshots/tn/screenshot_20070612_090340.jpg)
More screenshots here.
We're of course always interested in new developers wanting to help out. The code base is very mature and constantly being developed, so if you want to help out feel free to contact me.