The Witcher 2: Assassins of Kings will be available through GOG.com alongside its retail debut in May, 2011. Eurogamer reports the news will be made official later today. Both Witcher and GOG are overseen by Polish company CD Projekt, so the convergence doesn't sound, as the people of Mypos would put it, "ridigulous."
CD Projekt's GOG site hosts a number of "Good Old Games" and, when the company isn't performing poorly conceived marketing stunts, its DRM-free download service is focused and fantastic. The Witcher 2 will break new ground on the service by not being old -- let's just cross our fingers that it can at least live up to the other criteria.
Update: CD Projekt has confirmed the game will be available DRM-free on GOG.com, pre-orders available now.