http://www.nvidia.com/object/GeForce_MacOSX_18.5.2f16.html
There are drivers version 1.5.49.
Install manually by Pacifist
With my Geforce 9600GT 512Mb (deviceID=0622) OpenMark increased from 1139 up to 3300!!!
These drivers support GTX285 with CUDA technology as well as all older NVidia card (as I see)
Click to view attachment
Click to view attachment

Geforce 9800 GTX+ via NVEnabler here.

Pretty cool, the new drivers boosted my OpenGL 1.1 and 1.2 scores by 200 FPS in OpenGL Extensions Viewer, both are past 4000 now.

My Hackintosh is an iMac9,1 at this time so therefore the drivers won't install on it - the installer checks for MacPro3,1 or 4,1 and will only run on those models.

But as Netkas says, "did it ever stop somebody?" You can install the drivers on your Hackintosh like this:

Open System Profiler and make a note of your model identifier
Copy the installer package from the .dmg to the desktop
Right-click it and click 'show package contents'
Drag the file distribution.dist to your desktop and open it with TextEdit.
Find where it says MacPro3,1, replace it with your model identifier and save the file.
Delete the original distribution.dist inside the installer, drag your modified one in and type your password when prompted.
Run the installer, reboot when prompted
Profit

Note - of course you might need to add your device ID to the new drivers for them to work, read about that here:
http://www.projectosx.com/forum/index.php?showtopic=4

CUDA drivers and development tools for OS X available from here:
http://www.nvidia.com/object/cuda_get.html
If anyone comes across any precompiled, downloadble CUDA demos that run on OSX please let me know.

my laptop has a non standard resolution 1366x768, and with apple kext all i could get was a black screen
with these new kext i get full qe ci with external monitor support and all i needed was to set GraphicsEnabler=Yes in the boot.plist... using chameleon 2 rc2 ofcourse

acer 6930g with nvidia 9600m gt 512mb (0x064910de)