I believe "Python in a Nutshell" has a couple of clear examples using Queue and Threading, including one with a pool of worker threads that wait for entries in one queue and place results in another.
Also you should look at the Python Cookbook, which probably includes the same or similar examples from the Nutshell book, since the author of that is an editor of Cookbook. http://aspn.activestate.com/ASPN/Cookbook/Python?kwd=Threads -- http://mail.python.org/mailman/listinfo/python-list
