For those interested, the Quadro 4000 scored 23.46fps under 10.6.5 in Cinebench 11.5. The same card scores 55.90fps under Windows 7 64bit with Nvidia's 265.90 drivers.
My system is a 2.66ghz Mac Pro 4,1 Nehalem single cpu 2009 tower with 12gb memory.
It seems that yes, both ATI and NVidia are responsible for the drivers for their respective cards, but Apple provides the libraries that those drivers can interface with. Just as Snow Leopard vastly improved OpenGL2 support, it is likely we'll see something similar with OpenGL3/4 support in Lion.
so dredging up my cinebench results from when I got my 5870 last month:
Cinebench 11.5 OSX 64bit:
OpenGL GT120 15.36
OpenGL HD5870 24.32
Cinebench 11.5 Windows 7 Professional 64Bit
OpenGL HD5870 44.67
just to reconfirm those results, now that I've burned it in for a month, I presently get:
(CB 11.5 as above 64 bit)
OSX 10.6.5 25.21fps (and that is with dual monitors now attached)
win 7 prof. 64 bit catalyst 10.11 (driver vers. 8.791.0) 43.22fps
OK I also decided to check with the new catalyst package that just came out on the 13th vers. 10.12 (new windows 7 catalyst control center preview package)
so win 7 professional 64 bit, catalyst 10.12 (driver vers. 8.801.0)
open gl (CB11.5 64bit) 45.33
(the CB bench references show a quadro FX5800 on a Boxx 8520 octo 3.33 to be 45.52fps)
So this shows that what, the quadro is at least close to the 5870/5770 (tests have shown that the 5770 scores about the same as the 5870 in osx) in osx, but seems faster in windows (no big big surprise there)
I have a 2.26Ghz octad (early 2009, MP 4,1) with 6gb ram