I realize it comes down to legality, but I'm not sure why Apple wouldn't want people to run their OS on non-Apple hardware.

I'm running Ubuntu 9.10 on an old Dell Inspiron laptop but need iTunes to sync my iPhone. As a result, I installed VirtualBox and XP as a guest OS. If Apple allowed me to run their OS in a VM on non-Apple hardware, I would have installed Leopard instead of XP.

IMO, as long as you purchase the software, I don't see why you shouldn't be able to run it on any platform--especially, for Apple, if it means NOT running a competitor's OS. But that's just me...