I am no lawyer, this is not legal advice.
But I spoke to someone I know who graduated from Yale Law what his perspective on the issue was, and his opinion was that Apple could possibly be liable for antitrust behavior. (Again, this is not legal advice!)
From the way I understand it, what Apple is doing is taking some "monopolized" product (their OS, which only they can sell), and tying it to the REQUIRED USE OF some other competitive product (their hardware). This is bad: it's essentially what MS got in trouble with when they required people using Windows to also get IE, WMP, etc.
Imagine me selling you a super-special car, but saying you could only use it if you used my branded tires, oil, gas, filters, windshield wipers, etc. on it. I'd be taking one unique item (the super-car) and using it to sell my oil, gas, filters, wipers, etc without any competition. I can't do this legally, it's a violation of anti-trust laws. If someone else makes generic oil that works in my super-car, I can't prevent him from selling it to you (or you from buying it), that's illegal.
That's what Apple does when they sell OS X and require it to be only used on their computers. It's scummy. Outside of all the debate over quality, "just working"-ness, "Apple support", and whether or not they're "overpriced" or carry a "Mac Premium", what Apple's doing is probably a violation of anti-trust laws, and is just plain scummy.
If it's gonna run like crap on my hackintosh, I don't see how that even enters into the debate. The question is: is what Apple's doing here illegal, and if so, they need to stop.
Once that happens, every Tom, Dick, and Harry will be writing $20 apps that make installation of OSX on PCs as easy as 1-2-3, and releasing drivers to make it run well. Motherboard manufacturers will work out EFI booting, and MS will finally have a reason to make the switch. Then MS will have some real competition, Apple will have some market accountability to the quality of their hardware (not that it's all lacking, but 6 months into my macbook the plastic is falling apart...), and the world will be a happier place.