The BlizzCon schedule offers the following explanations of the custom maps, snapped by our Brian Leahy, who's on the show floor and will doubtless try them later.
Aiur Chef takes you to a remote area of the planet Aiur, where aspiring zealot chefs skilled in the arts of cooking and killing compete for the title of Executor Chef. Test your wits in the puzzler StarJeweled, which challenges you to match jewels according to color to gain energy, train troops and crush your enemy's base. You'll also be able to team up with a friend to fend off a new strain of zerg infestation in Left 2 Die (a new co-op take on the StarCraft II campaign mission "Outbreak"), as well as wage war with the most powerful heroes in the universe in Blizzard All-Stars, an explosive new multiplayer scenario.
There's no word yet on when the maps will be released to all and sundry, though we've loaded up StarCraft II and had a peek to confirm that they're not out yet.