My thoughts exactly... This is my first MP, but I always remembering them pairing nicely with Nvidia and was pleasantly surprised to see the 670 at the top of the list and the most inexpensive high end card out there, and like you point out with phenomenal i/o and power consumption.Probably. They hit the sweet spot for Apple to green light them. Price/ performance/ power. Too bad Apple's got an issue with Nvidia. I am sure that whenever the drivers start showing up (if they do) you'll hear about it here.
I can understand that the MP is a VERY limited market and piece of their customer base, but it is a little strange that they wouldn't at least come up with a little upgrade since 2010 before they kill it off for good.
The thing I'm really interested in now is sticking a logic board from a MBP into a case I'd build a windows machine in. From looking at them, they're almost the same size as perhaps a big raid card or video card.