If these requirements are real, I expect to see this during game intro:
http://pcper.com/images/news/amdgamingevolved.jpg
heard some news about the game will indeed be on AMD Gaming Evolved banner quite sometime ago. when the spec like 480 and 5770 are listed on the same tag on recommended card needed it kind of confirm the news lol.
http://www.hardwarecanucks.com/news/games-news/amds-gaming-evolved-program-snags-far-cry-3/
i like the idea about the gpu maker working closely with game dev to optimize the performance on their hardware but honestly i don't like the story when the dev already sponsored by company A it will shut it doors to work with company B. (like the one happen with that holy Batman game lol).