This is not absolutely a graphics glitch but there are glitches of that kind I experienced too. The main problem came from The Witcher 1 where (my best guess is) the program had some kind of memory leak because from time to time the map disappeared only icons remained and at that state trying to save the game caused immediate crash to desktop. Now in Witcher 2 I've experienced this map disappearing bug sometimes, but CTD's occur very often. Even when I try to communicate with an NPC.
Graphics bug I experienced: backgrounds disappear totally, only NPCs and the ground they stand on remain.
http://kepfeltoltes.hu/110826/witcher2_2011-08-26_18-21-05-20_www.kepfeltoltes.hu_.jpg
I could not regenerate the map disappearing bug and take a screenshot but I could regenerate a CTD by loading 2 or 3 different saved games, entering the inn in Flotsam and visiting rooms in it then hitting the Map key on my keyboard.
My game is patched to 1.35. I use nVidia 280.26 display driver and retail version of the game.
While I tried to register to the forum to post this I experienced another bug: I have a GoG account but I couldn't sign in with that. No matter, I tried to create a new account for en.thewitcher.com. Unfortunately the engine didn't allow me to use the email address associated with my GoG account. Not a major problem (I used another e-mail address which I do not use regularly) but it's a bug imho.
I hope these bugs will be corrected sometime.