Sony have today announced that they have licensed both the Havoc and the AGEIA PhysX physics API's for their PS3 developer toolkits. I would think this means we will see cusomised version of both API's designed to take advantage of the CELL cpu, thereby taking a big worry off the mind of most developers.

I would imagine that using either of the 2 API's would be a whole lot easier than writing a physics engine yourself, particularly on the somewhat unknown entity of a CELL cpu.