Perhaps ATI and NVIDIA's idea of using their own GPUs for the purpose of physics processing might not be such a good one after all, at least according to an anonymous games developer that is. He goes on to say AGEIA are on the money, with their standalone physics processing cards capable of offering far superior physics effects to that of a dedicated GPU for the task.
AN ANONYMOUS games developer claimed that ATI, Nvidia on GPU physics is not even close to what you can get with Ageia's Physics card.
He tried to implement the physics and said that to his horror he learned that ATI and Nvidia "cosmetically" affects the physics. The developer added that only Ageia can handle game play physics. The same level of physics quality cannot be achieved using GPU physics, and even high end cards such as X1900 XT or 7900 GT cannot handle it.