Blizzard entertainment in the recently concluded Blizzcon 2008, announced that Starcraft 2 will consist of 3 separate episodes. The episodes however will be sold separately and independently of each other. Each episode will tell the story of one race starting with the terrans, then zerg and finally the protoss. Some Blizzard fans suspect this is a marketing move to milk the award winning RTS franchise but Blizzard denies this and reasons that they have so much story to tell, episodic release is the only recourse.
Many gamers in various forums suspect this is an Activision move more than Blizzard since Blizzard and Activision have recently merged.