Recent Blizzard job postings seeking extra staff for a "Next-Gen MMO" were marked as "Top Secret" on the eve of Halloween, leading some fans to take the timing as a hint at the all-but-confirmed Diablo 3.
A follow-up to Blizzard's dungeon-crawler has been considered the company's next logical project, but as always with Blizzard titles, speculation continues to run rampant. Possibilities for the identity of the unknown title include the previously mentioned Diablo 3, an advanced version of World of Warcraft, or an entirely new IP. The term "next-gen," and the details of the positions, may also be indicative of PlayStation 3 or Xbox 360 development.
Yesterday's update included a new posting for a "Game Physics/Collision Programmer," asking for applicants with experience in Havok, Ageia and O.D.E. physics engines as well as multi-threaded programming skills. Previous postings include a bevy of 3D artists, suggesting that whatever the game is, production has ramped up to the key phase of asset creation.
The company is currently in crunch mode, tearing into StarCraft 2 and finishing up development on the next World of Warcraft expansion, Wrath of the Lich King
http://www.blizzard.com/jobopp/#programming