Source Code Access
If you are cool with Subversion, then you can download the code via the method described on the Google Code “source” page; in a nutshell it comes down to the following commandline:
svn checkout http://pymine.googlecode.com/svn/trunk/ pymine
…but do join the maillist because sometimes what gets put back is not in an fully-operational state.
Details of which versions are considered “stable” are posted on the pymine wiki.
Prefabricated packages for pymine – Ubuntu, and (soon) OSX – are available from the Downloads section of the project website.