OK Mac guys, I found this link to InsanelyMac forums from Twitter. So far it looks like a solid hack. Basically it adds your nVidia Cuda equipped GPU to the list of Mercury Playback cards. SWEET!! 

I know it is simple, I know it is exactly the same as with windows, but I am writing this guide because I know there are several other guides around but these are "windows only" and for some people this guide might just simply help:

REQUIREMENTS:
I will first list the requirements, later in the text every requirement will be commented and clarified.

• CUDA CAPABLE Graphics Card - ANY cuda capable card with more than 512MB should work, this is the beauty of the trick (more on this later).
• CUDA DRIVER INSTALLED AND UPDATED
• 64 BIT SYSTEM (CORE2DUO, ETC...)
• AN INSTALATION OF CS5 OF COURSE.

A) INSTALL THE LATEST CUDA DRIVERS FOR SNOW:

http://www.nvidia.com/object/MacOSX-CUDA-3.0.html

Once installed, go to System Preferences / CUDA and accept the update, there is no direct link to the latest CUDA driver, that is why you have to do the update from the pref panel. (If you know of the new drivers address let me know)*



HAVE YOUR CS5 INSTALLATION READY
I guess this does not need explanation.


C ) FIND OUT THE REAL NAME OF YOUR GRAPHIC CARD

Open a terminal emulator (c'mon do not be scared)

1- Go to the spotlight, type TERMINAL, press enter.
2- Now on the terminal type:

Click here for the rest of the hack