I can't point to anything "official" but I sense a little uncomfortableness between Apple and Nvidia.
I imagine that the ROHS thing has something to do with it.
http://support.apple.com/kb/TS2377
Read that carefully, Apple comes very close to saying that Nvidia lied to them about extent of thermal failures under G92 and it's brethren. Not often that Apple chokes up a 4 year warranty based on a 3rd party's inability to get their sxxt together. Imagine costs for replacing logic boards on a few thousand MBPs.
Basically, the 8800 cards based on G92 are now dropping like flies, as were the 8600 cards in that post. The lead free solder isn't nearly as pliable/forgiving as the old deadly stuff. Hence the multi-hundred post threads on baking these cards to bring them back to life.
I would also point to the fact that Nvidia released their own Mac drivers and told customers to skip the 10.6.4 update from Apple due to poor performance.
When Nvidia first released the drivers, there was Fermi support. Perhaps not an "accidental" leak? Those very drivers, less the crucial NV100HAL fermi kext, are now rolled into the upcoming Snow Leopard Graphics update.
I don't think ATI has ever done something like that. Almost feels like Nvidia is forcing Apple's hand, like they feel their GPUs are being hampered by APple's poor driver support.
And to think just a few years back, we got the GeForce 3 BEFORE the WIndows world. The good old days.