Apparently, the Russian publisher of The Witcher 2 decided to beat the Polish Playboy session of virtual Triss Merigold and decided to release a calendar with a nude model posing as Triss and a non-nude one (unfortunately for most female fans and some male ones) posing as Geralt.
Triss is a Ukrainian model known as Klodi Monsoon. You can see more pictures of her on her DeviantArt.
Here's a video from the photo shoot.
And some pics:
Myself, I'm still nerd-raging about Triss lacking her scars from the Battle of Sodden Hill that she's supposed to have according to the books.