The SixAxis controller was the offical controller that was shipped with the PS3 from launch. This controller can be used without too much hassle on the PS3 running Linux. More information on setting up the SixAxis can be found on the SetupSixAxis page.

The SixAxis controller has now been discontinued in favour of the DualShock 3, which will feature rumble support.

More information on the SixAxis can be found on it's wikipedia entry http://en.wikipedia.org/wiki/PlayStation_3_accessories#Sixaxis∞