It was bound to happen sooner or later, but a coder going by the name of Maxxus has hacked Mac OS X to run on generic PCs that meet some relatively simple criteria. Of course it isn't a very polished solution yet and it does require a bit of work to even get the system booted, but it's bound to improve over time.
With Core Duo enabled PCs going for up to $1000 less than an Apple Core Duo machine, there are plenty of people interested in running Mac OS X on a generic cheap PC. The catch is that you have to have a legal copy of the Mac OS X DVD that came with a Mac Core Duo and getting the system working on a generic PC isn't for the faint of heart. Apple would probably consider this type of activity illegal, but it won't stop people from trying.