I tried to use the threading module to start the XML 
RPC server in a different thread (xmlrpcServer itself 
also is a threaded piece of code), but that seems to 
conflict with the mainloop. If you start this 
application, it starts the thread, starts the mainloop 
and stays in there, once you finish the mainloop, the 
thread continues.

You've stumbled on a bug in Framework.mainloop(): it 
doesn't know anything about multiple threads. It gives 
time to other applications (by calling WaitNextEvent) 
but not to other threads within Python.

Also see
http://mail.python.org/pipermail/pythonmac-sig/2002-
April/005416.html

and 

http://mail.python.org/pipermail/pythonmac-sig/2002-
April/005428.html