Forgot to mention in the original post: PySide is naturally available on the desktop as well, which might come handy when testing the code. The different download links are available at:

http://www.pyside.org/downloads/

Packages are available for the major Linux distributions. In addition to that, Mac OS X packages should be available via Fink (can't verify, I'm not a Mac user). Windows porting work is ongoing and we hope to have results really soon.

So far we haven't packaged Qt Mobility to other platforms than Maemo 5 since many of the most interesting APIs are missing e.g. on desktop Linux.