with the arrival of GNOME 2.28 Telepathy defacto lib for IM: Port Gajim to Telepathy is not a bad idea
they appear to have some python bindings. Sooner or later Gajim should use this standard framework and make sure it evolves as it should. I don't know what the jabber implementation currently supports nor if the python bindings wrap 100% of the lib.
The lib is also not gnome dependant AFAICT