Vault_Boy: From what I have readso far the 360 pad is easily the controller that is recognized by most games
Miaghstir: On Windows, where XInput is available by default, yes. And that's only recently, before that became available on PCs, pretty much all DirectInput devices were equally supported (I don't know about the PS3 controller, but I suspect its drivers register it as a DirectInput device like most other gamepads and joysticks).
This topic was about Mac OS though, not Windows. And I have little knowledge of controller support on that platform, the only thing I remember is GameSprockets from Mac OS classic.
They made drivers for the PS3 pads and they work flawlessy, pairing on bt or via usb, can even emulate the XInput like a 360 pad so on Windows it'a all a matter of preference which layout you like better :P