the situation is pretty problematic, I hope someday scipy will add a python package for rotating and interpolating quaternions, up to now:
- http://cgkit.sourceforge.net/doc2/quat.html : slow, bad interaction with numpy, I could not find a simple way to turn a list of N quaternions to a 4xN array without a loop
- http://cxc.harvard.edu/mta/ASPECT/tool_doc/pydocs/Quaternion.html : more lightweight, does not implement quaternion interpolation