In an official press release AMD and Blizzard Entertainment announce their future cooperation.
At Blizzard's own convention, the Blizz-Con, the first fruits of this cooperation will be seen in early October. AMD supplies the graphics cards for all the PCs that can be used for playing the Blizzard products at the convention.
AMD has been working with important studios, like Valve, before. So it might be possible, that there isn't a Black Box gift coupon in the box of the graphics cards but possibly one for Diablo 3 of Starcraft 2.