Sorry, but maybe you should actually read what I wrote and take a moment to process it before responding to what you incorrectly think I am arguing. My whole point was that yes, Apple writes these drivers. Why? To avoid the scenario I'm talking about that you run into in the Windoze world. Internalizing this process, however, while continuing to provide a benefit WRT stability, significantly holds them back from having the latest and greatest in hardware (and the accompanying software drivers to push that hardware's performance).
AFAIK most GPU families have similar internal specifications. So if a 8800GT works there is no real reason why a GTS GTX GS and Ultra wouldn't work. Especially if Apple is using OGL, the hardware is abstracted they aren't writing to the metal (seems to defeat the purpose of using OGL). What is sounds like to me is a firmware (EFI version vs BIOS) problem. Now the interesting thing is blame Nvidia for not making an EFI card. But what people may not realize is only AMD/ATI sells video cards directly. Nvidia only sells the chips. And since Apple is pretty closed in respect to video hardware, 3rd party folks (EVA, XFX, etc) probably don't see a huge source of profit for supporting Macs. It isn't like they could charge more when all it takes is a firmware flash to get the "PC" card working in the Mac. Really the only thing I could think of is disabling stream processors as a means to prevent "PC" cards from being used in the Mac. And all that would do is irritate people even more.
Lets just all sit back and see what happens. I wonder who is actually making the cards for Apple...