Here is link of Avid supported systems with Hypertown. You will find that 8800GT is supported only and only Mac with 10.5.x. (not 10.7.4).
However it doesn't mean that will not work with some basic operations.
I am testing beta 6.0.2 which will be released in 2 weeks time, and there is still problem on Digital Cut on Mac.
We have tried 4 qualified mac's and all of them have problems, even on local/fast HDD's. It happens randomly and you also need to have console window in order to notice this bug.
When you doing Digital cut, also if you click "about this Mac" it will stop. (it tells you about quality of program)
Mac with 5.5.x and PC with 5.5.x or 6.0.1 there is no issues on DC, and only happen on Mac V6.
Considering that this is first ever 64Bit application as well with support 3rd party I/O hardware ever, we could expect some problems but not such a basic miss.
It's my understanding that Avid does not use the GPU for any acceleration on the Mac. Any card qualified by Apple on your machine is fine with Avid. Apple provides all graphics card drivers in the Mac OSX install and software update. Normally, you do not need to download them directly from Nvidia or AMD. Avid on Windows does use some GPU acceleration (which is minimal compared to Premiere Pro or Final Cut Pro X, which use the GPU extensively), thus there are recommended driver packages to use on the Windows side.