It has been a long time since Epic Games revealed anything that wasn't Gears of War or Unreal Engine related. That was until this weekend. No info is really available other that the fact a new game is in development. Cliffy B said so.
At an Epic Games panel this weekend at PAX East in Boston, featuring president Mike Capps and creative lead Cliff Bleszinski, both admitted they were working on a PC-only title. Capps told Joystiq after the panel that the game was already in development and it would stay exclusive to the PC.
Keep in mind that these days, PC-only could mean a casual game or a social game, but given the track record of Epic as a hard-core shooter developer, we can only hope that the project would be another game in the Unreal series.