Starcraft II's custom game support for Custom Games has been weirdly flawed. On the one hand, there's the great editor, and the tools available for modders. On the other: there's odd restrictions on custom map sizes and their scope, and the tools available to players to find those games are just awful. That should change with the release of the Starcraft II Arcade.
The importance of the update is best signified by the changes in the UI as you open the game: the top left corner now offers two options. One is for Starcraft II - comprising single player campaign, multiplayer and challenges. The other: the arcade.
Think of the arcade as an iTunes equivalent for Starcraft II custom maps. It allows users to download and play maps through a better interface, but also for users to review, rate and promote their favourites. The best map in there so far that we've played? A bomberman clone. Aww. The oldies are the goodies.
The Arcade should procede the Battle.net Marketplace - which is set to allow modders to charge for their maps.
To try it out, you'll need to download the Arcade installer from your Battle.net account.