techpowerup! has reported that Anti-Aliasing (one of the most basic image enhancements in any game) is only enabled in Batman Arkham Asylum on Nvidia cards. ATI confirmed this by doing tests in their labs where they changed the ID of their GPU to emulate a Nvidia card which then turned AA on again.
Bug or intentional foul play? You decide.
Read about it straight from AMD’s Ian McNaughton here.