This is interesting -- the costumes at BlizzCon have gotten more and more complicated every year, as people try to one-up each other by bringing the wackiest and biggest costumes to wear, both for the official contest and around the show floor (you can see some of last year's appearances below). The big winner last year was this turtle mount, complete with wheels and a moving head, and so we wonder: what'll happen this year?
Not so fast, says Blizzard. When a player asks just how far costumers might go (a live mount?), Bashiok says that there are some tweaks to the rules this year: costumes can't go over 10' in any direction, include "liquids or messy substances," or be judged on items that can't be worn or held. That would seem to disqualify the turtle mount, from official judging anyway -- they want the contest to revolve around costumes, not vehicles.
Which doesn't mean that we won't see some crazy costumes on the show floor (and obviously you'll see them here on the site, even if you're not in Anaheim). But the contest itself might be a little more low key than last year -- seems like the Sea Turtle/ATV was enough to make Blizzard dial it back a notch.