Yep, later this year!
The news broke out of a pre-E3 event the company's holding this afternoon in California.
CD Project is calling the Xbox 360 version an "adaptation not a port" but wants to bring the "same experience as delivered to the PC players" for Xbox 360 owners, including many of the improvements the studio is incorporating into the PC version.
The Xbox 360 version will be at E3, too. I'm gonna have to track that one down. I've expressed my interest in playing The Witcher II, but I don't have a PC capable of playing it. No problem!