In case you've been following the work on a native launcher for Python apps on BBX (PlayBook), you'll be happy to I've just set up a BBX-Python project web page with the code hosted the bbx-python bitbucket repository.
There's a downloads folder (not using the Bitbucket one... wouldn't let me upload because of some Amazon service crashing apparently), with a first release of the launcher. Also a wiki page with Quick Start instructions to get you going, and some sample code.
One fellow (artoo) in the IRC chat (#bbx-python on freenode.net) has already written an extended launcher in Python, which uses a "popup" dialog to show you a list of other Python scripts from which you can select one to run.
Note
As of June 2012, we've renamed this the BlackBerry-Py Project. You can follow news about it at @BBPyProject and the web site has moved too.