Cuda on the Mac Pro is a big thing though, and for years now NVIDIA have been the only ones to offer several generations of cards that just work in the Mac Pro, either via OSX drivers or drivers Directly from NVIDIA.
This gives me good OpenGL, CUDA, and OpenCL
What I don't like about the new mac pro is forcing people to have to have Dual GPU's, and making them AMD only, along with what looks like a proprietary board for them.
Also Phil taking about how we know how expensive the D300's are, is all rubbish. There's no data on the cards at all, although looking at the specs they look like rebranded and weakened FirePro W5000s. Okay cards, but not amazing.
People have already see that flashing a normal 7xxx card with the Apple EFI, get's the card recognised as a FirePro in Mavericks, while in Mountain Lion they're still seen as AMD Radeon 7xxx series cards.
Considering the new D300, D500, and D700's don't have as much RAM as the current Firepro's I think they could just be flashed normal cards. I also don't recall seeing ECC memory mentioned on these new cards for the Mac Pro. :/
All in all the base spec Mac Pro looks rubbish in all specs, bar the SSD Speeds, even then 256GB is kind of small considering you'll have to heavily invest in Thunderbolt external storage arrays which can cost around half the price of the machine it self.
I paid £1850 for the Mac Pro in my signature, and if you look at benchmarks for multi-threaded work for the new Ivy-bridge, compared to my current CPU, there's not that much of an improvement.
http://www.guru3d.com/articles_pages/core_i7_4960x_processor_review,12.html
And that's with the new Flagship CPU being 6 core variant.
This means that the new Quad-core mac pro will perform quite similar to my current system, if not just barely inching ahead.