Leading me to: http://sgillies.net/blog/829/shapely-1-0-8/

"The same problem [segfault] could afflict any python package that
uses Ctypes on 64-bit systems without explicitly marking argument and
return types. "

Looking back through the modwsgi thread and this one, everyone's on
64bit, except the CentOS guy who said it worked ok on 32bit but not on
64bit.

Maybe thats the problem with the ctypes+geos bindings in GeoDjango?
I'm running something-pre-1.0, but I can try it on a trunk checkount
to confirm the same symptoms.

Rob :)