I thought there was probably already an official mascot. There's a little green snake with his tongue hanging out on the left of the URL when you visit www.python.org. I see it in my Safari browser on Mac OS X and in Firefox, but not in Internet Exploder. I thought that I had seen a large picture somewhere, but can't find it now. I don't know if he has an official name, but I've been calling him Monty. Monty, the Python; not to be confused with Monty Python of course ;)
Dan -- http://mail.python.org/mailman/listinfo/python-list