Apple keeps tightening intel builds
According to sources who keep trying to install the OS X/intel version from the developer kit machines on the "any PC", Apple continuously changes things around to make it harder for the hackers. The latest known build of OS X/intel is Mac OS X 10.4.3 8F1099, which is said to "work fine on Apple's machines" but apparently has not yet been brought to run on any other X86 machine.