The StatusNet Desktop and Mobile clients use the cross-platform Titanium toolkit, which provides a nice JavaScript environment with various native platform access.
For full directions on building, see:
http://status.net/wiki/Building_StatusNet_Desktop_from_source
The StatusNet Mobile build requires copying some shared files which currently reside in the StatusNet Desktop subtree.
For full directions:
http://status.net/wiki/Building_StatusNet_Mobile_from_source
Note that the 'StatusNet Tablet' and 'StatusNet Blackberry' folders are stubs which copy most of their contents from the Mobile dirs.
Some code for StatusNet Desktop is based on Tweetanium:
Tweetanium was one of the first reference applications for the Titanium Desktop SDK. Based on the awesome work of the Titanium development team and community, I figured it was time to bring it back for both desktop and mobile. We'll see where the project goes - maybe some people will like it enough to use it? In any case, it will serve as a good example for folks looking to build desktop and mobile apps with Titanium.
Like Titanium, Tweetanium is licensed under the Apache 2.0 open source software license.