Here's a better analogy that I used today to think this through myself.
Let's say I purchased a book written by Steven King. Now let me ask a series of questions.
1) Does it violate copyright for me to sell the book? No.
2) What if I wrote some notes in the margin and my name on the inside front cover? No, still ok to sell it.
3) What if I draw lines through the last page, write my own ending on the backside of the page, and slap a sticky on the front of the book saying "includes the 'saltyzoo' ending!"? Probably still ok, if it's one copy.
4) What if I do #3 and begin mass production? I'd probably be sued to the stone-ages and lose badly.
So then, I asked myself these questions.
1) Forget the law, does it *harm* Steven King for me to sell the book as described in #1 above? No, he sold one book, and there is still only one book out there that has been paid for.
2) Does it *harm* Steven King for me to do #2? Nope
3) Does it *harm* Steven King for me to do #3? Nope, he was paid for the copy of the book, he is getting full credit for writing the book, the changes I made are clear to anyone that can see well enough to read, and they know exactly what they are buying, my work cannot be confused for his, and vice-versa.
4) Mass production of #3. Here's where it gets sticky. Deep down, I don't feel that he would be harmed. But the problem is that he *may* be harmed by what I'm doing. So it's difficult to take that away from him.
I really want OS X to be opened up. But when I look at it objectively I cannot argue with the fact that it is violating Apple to allow this to happen. I really, really want to be wrong, but sadly, I'm not. If only they would do it themselves.