PlanetDiablo received a letter from Blizzard Entertainment regarding the release date for Lord of Destruction, the upcoming add-on for Diablo II (thanks Shacknews). They were told that it's set for release at the end of June, but the letter went on to hint at a major, surprise announcement at ECTS this September, which will not be Starcraft 2, but an entirely different game. Here's all that was said about this supersecret game:

Our next big announcement is at ECTS [European Computer Trade Show] this September. It's not Starcraft 2 (the people who would be doing that are doing W3), but I can tell you without exaggeration that this is a huge announcement and one that will dominate coverage of the show. I can't say more about the game at this point, but the stuff you see rumored on the Web is pretty far off the mark. This fall is going to be a very exciting time!