Blizzard just announced in the live videostream that Starcraft: Ghost will have playable Zerg characters in the Multiplayer mode:

  • Zergling
  • Hydralisk
  • Mutalisk
  • Infested Terran

We will get you more details when it becomes available.  This info came straight from Mike Morhaime—president of Blizzard Entertainment—in the live videostream held by WCRadio