According to the recent official BlizzCon update, StarCraft 2 will be playable at the upcoming BlizzCon !

Visitors to BlizzCon 2007 will be treated to the first-ever public hands-on with StarCraft II. Demo stations will be set up at the convention, and attendees can sample the new units and gameplay elements for themselves in multiplayer battles. We’re excited to offer this exclusive opportunity to our players, and look forward to seeing you at BlizzCon.

The announcement also means that not only is the 3D engine ripe for simplistic presentations of gameplay, but the game’s mechanics already support multiplayer action, or will at least start supporting it by August 3, 2007.