The Xbox 360 version of The Witcher 2: Assassins of Kings has just been officially announced in an Optimus stock market filing (in Polish). Optimus is the parent company of CD Projekt. The company announced a publishing deal with Atari in North America for the console version, just like with the PC edition.
Some Polish stores have already announced the release date as November 15. We'll likely learn whether it's true during the conference.
The announcement was made during the ongoing CD Projekt Summer Conference, during which we're likely to learn additional details.