Mac OS X for x86 is fine, but I think Motorola will try hard to keep Apple using their PPC architecture for their mainstream machines. This is just a back up plan for Apple incase Motorola does act stupid.

HOWEVER: the question that will be on everyone's mind is how will Mac OS X on x86 perform compared to other operating systems on the market. x86 being the resource hungry architecture that it is might not meet the demands of Mac OS X. If Mac OS X comes to x86, it will come to high-end workstations.