Just to clarify. One can still tell WSGI applications under mod_wsgi to run in the main interpreter and in that case modules using PyGILState* do work. By default though, sub interpreters are used as noted.

The mechanism for forcing use of main interpreter is the directive:

WSGIApplicationGroup %{GLOBAL}

Some details about this issue can be found in:

http://code.google.com/p/modwsgi/wiki/ApplicationIssues#Python_Simplified_GIL_State_API