Having to use multiple processes and socket communication in order to spread the load of computationally intensive tasks? In 2008? Come on.
Guido van Rossum and several others think that this is the right way to go -- and that "multithreading is evil": http://www.eecs.berkeley.edu/Pubs/TechRpts/2006/EECS-2006-1.pdf
Personally, I like using threads, especially in network and database GUI applications.