A formidable Lisp bot, written by a Hungarian programmer, is leading the rankings by a respectable margin in the latest Google AI challenge: http://ai-contest.com/rankings.php
Let's cheer him on, and hope he stays in 1st place :)
I found out about this challenge too late and, although I played around with the Lisp Starter Pack last week, didn't have time to write a decent bot. I believe there will be another challenge next year.
Vish