Starcraft II: Heart of the Swarm, the standalone expansion that will feature the Zerg campaign, will be shown off in May.
Kotaku reportedly received an invite to see Heart of the Swarm earlier today, being promised they'd see a small portion of the game's campaign, but were also warned that they wouldn't see any of the changes or new units that would be in the final product. It's expected that Heart of the Swarm will include some RPG-like mechanics and perhaps include new Zerg units.
They were also advised not to expect Heart of the Swarm in 2011.
Heart of the Swarm demo in May
25 April 2011 | By JonahFalcon