Ageia told the press at Siggraph 2005 that world's first Physics Processing Unit (PPU), the PhysX, will start shipping this fall. The first hardware is already running out of the fabs and Asus (and others) is prepared to sell them worldwide.
It is on track to bring this hardware into retail by the autumn, we could not get anything more specific than that. The company is mainly waiting for the game demos as it needs to ship the game content with the cards. You can compare its position with 3DFX when it launched the Voodoo card as AGEIA has to convince people that you need physics acceleration just as 3DFX had to convince people that you actually need 3D acceleration.
The first games that support the PhysX are expected around the launch and Ageia believes game developers will bring out patches for retail games to support the PhysX card. More details at The Inquirer