I think I saw a video of this a while back, it looked very impressive.. thousands of barrels, girders and other objects being thrown around.. it gave the impression that it could handle any number of calculations.. Imagine.. a WW2 game where everything is destructable down to the brick level and flying bricks and mortar do damage to other things... real collapsing scenery, not just the scripted stuff we get at the moment... all of this being handled by the card while the CPU handles the orchestration of Graphics, Input, Sound and Network leaving the Video rendering, lighting and effects to the Graphics card, The Sound processing and effects to the Sound card, the Network management to the Network card. As long as the data transfer speed wasn't a problem (I imagine that you'd send all of the entity data to the physics card, it applies forces and deforms meshes which are then extracted and sent to the video card for transformation and lighting.)

But it does move the PC away from the Generic Do-Everything machine towards a Hardcore Gaming only machine which is essentially what a console is for.