It could be completely wrong - Blizzard has made no comment yet - but several U.S. retailers have adjusted their product listings for StarCraft II to show a release date of 3rd December. BestBuy, CircuitCity and GameStop are all showing the new date.
The synchronisation suggests the retailers took the date from an official release schedule (rather than just making it up - which also happens). Being from a schedule doesn't make it right though; in the absence of any official announcement, and this far out from release, the dates on a schedule will be very much subject to change. Nevertheless, this is a good sign that Blizzard wants the game out in time for Christmas.
The Blizzard web site is showing a splash page this morning, with what looks like a blue burst of energy surrounded by darkness. It's not clear if this is related, but Blizzard often creates teaser pages before major announcements.
StarCraft II is a sci-fi RTS, the long-awaited sequel to 1998's award-winning StarCraft. The developers have described it as the "ultimate competitive real-time strategy game." It will be a PC exclusive.