A user comment sums it up: "Developers are unlikely to make gameplay dependent on the presence of a PPU until it's widely adopted. Until then it'll probably be limited to effects (and taking the gameplay physics load off the CPU)." As PPU adoption becomes more widespread, developers may embrace it, but we need developer support to make the case for adoption -- it's a vicious circle that AGEIA will have to break.
To further fan the flames around physics acceleration, a source close to the DirectX steering committee has told Joystiq that Microsoft's DirectPhysics API may not be going ahead after all. Instead, Microsoft may approach a laissez-faire attitude and snap up whichever acceleration solution emerges as the winner.