Just curious: Where have you read that the Mac-x86 hardware will be able to run Windows? And even if that's true (and it might be), that doesn't mean that a non-Apple x86 PC will be able to run MacOS X.
A boatload of the stuff that makes a Mac a Mac is in the ROM chips on the motherboard. Without the ROMs, a PC won't be able to run the software. (Recall that the Mac 68k emulators that ran on PCs, like [link|http://www.emulators.com/softmac.htm|SoftMac], needed a ROM image to do their magic. AFAIK, there isn't a similar PPC ROM image available for x86 - at least not one that is outside of Apple.)
There are certainly ways of getting the ROM image out of a PowerMac and into a form that can be used on an x86 machine. However, it's not clear that such work is easy - if it were there would have probably been Mac PPC emulators out there by now.
So, I doubt that Apple will stand for non-Apple hardware running MacOS-x86 any time soon. Steve really doesn't like clones. Remember Franklin? Remember that one of the first things he did when he went back to Apple was to kill off the clones.
My $0.02.
Cheers,
Scott.