I wrote a wrapper around the PostgreSQL implementation of setproctitle 
(probably the most portable around). I've only tested it on Linux: 
probably will require tweaking constants to compile on other platforms 
(something postgres does at configure time) but the core functionality 
is surely well tested.

I've put the module on http://code.google.com/p/py-setproctitle/ : 
testing (yes, there is an unit test) and tweaking setup on other 
platforms is welcome.