Blizzard Entertainment's BlizzCon is always a massive success, so the fact that there's another one schedule for this year isn't a shock. Now you can mark it on your calendar, though: BlizzCon 2011 is taking place October 21 through October 22 at the Anaheim Convention Center.
No details yet on ticket availability, pricing, and all that jazz. We also don't know what to expect this year, but my guess is that Diablo III will be playable (but still not on shelves), you'll get a free World of Warcraft mount or something for attending, and the show is going to sell out. Fast. Plan accordingly.