Update: Here’s the trailer!

Ahead of the announcement planned for later today, Activision’s UK branch has jumped the gun and officially revealed Call of Duty: Black Ops 2. According to the official UK website, the game is set in the near future, and will will thrust players into a 21st Century version of the Cold War, where technology and weapons have converged to create a new generation of warfare.
The game is being developed by Activision subsidiary Treyarch, the same studio behind the original Black Ops. Call of Duty: Black Ops 2 will deploy on November 13, and will be available on the PS3, Xbox 360, and PC. Expect more details on the game to arrive later today.
Link: Official UK Site