If true, I would say it's an attempt to combat companies like Valve/Blizzard supporting Mac and even Linux. MGS used to be a pivotal asset in making PC gaming seem like a Windows only affair, but now Lionhead has gone Xbox exclusive and they shut down Ensemble and Aces. That leaves it to third parties, and as Sony knows, you can't leave it to third parties to carry your banner for you.
It would probably also have the dual aim of making Natal popular with the PC crowd (assuming Fable III substantially supports Natal in some way).
Seems silly to bring Fable III to PC and not Fable II, however. I doubt this would happen.







