There's lots of speculation on what Blizzard will announce later this month in South Korea.
It's not yet sure what it will be but most people agree that it may be a new Starcraft game. There are two probabilities: the first one is that Blizzard will announce a RTS game called Starcraft 2, the second one is that they may launch a Starcraft MMO. This could become something like World of Warcraft but in the Starcraft universe.
"We do intend to announce a new product at the Worldwide Invitational next month in Korea, and we appreciate the enthusiasm and interest in getting an advance look at what that will be, but players will have to wait until May 19th to find out more. Also, we have a very strong connection with the characters and settings of StarCraft, and we do plan to revisit that universe at some point in the future, but we don't have anything new to announce in that regard at present."