Charlie over at the Inq re-examines the software-based physics rendering that challenges Ageia's way of doing things (dedicated PPU), & comes to the following conclusion:

"At some nebulous point in the future when GPU power is plentiful, and you can dedicate half of your graphics performance without having to drop the rez of you game, then I would say save the $250 on the PPU and go the software on the GPU route. Until then, the software route is a tough sell in the bang for the buck stakes."