It would be more appropriate to ask this question on the XBMC forum, but it is down for maintenance and weekends don't last forever!
What version of Python does XBMC 12.0 use and/or require a plugin to be written in? The prerequisites
section here states:
Python interpreter 2.4 (use the same version as XBMC or version <= 2.7 ) install on the machine running Eclipse
... which suggests that some unknown version of XBMC once required a version of Python 2.4 <= N <= 2.7
On the other hand, the scripts and plugins section
here suggests that maybe version 2.1.0
or 2.0.0
may be required/used.