There's some discussion and early examples here: http://www.teamliquid.net/forum/viewmessage.php?topic_id=105570

You might also look at some of the custom AIs for Total Annihilation and/or Supreme Commander, which are reputed to be quite good.

Ultimately though the winner will probably come down to someone who knows Starcraft well enough to thoroughly script a bot, rather than more advanced AI techniques. It might be easier to use proper AI in the restricted tournaments, though.