I have recently bought a PS3 controller with the intention of getting it working on OSX. I have been successful, and will be released a GPL OSX driver shortly.
The HID descriptor reported by the device appears to not support the spacial information reported by the controller, or the pressure information reported by almost all of the buttons on the device. I am working on a means to expose this to normal applications in OSX, although I have not yet decided how.
Using information gathered around the internet I also believe it will be relatively simple to add Bluetooth support to use the controller wirelessly. However, this is not yet complete.
Thus, as an interim solution for people who just can't wait for my finished driver, I provide a basic driver which simply allows the controller to work on OSX:
WARNING: Note that for modern versions of Mac OS X there is a PS3 driver built into the OS and this driver is not required.
However, I believe the built-in driver does not turn on the extra PS3 sensors, so these will still require a custom driver to access presently. I've sadly been too busy to work on this project.