Tessellation is a directx 11 feature, but you could find a tessellation unit in the radeon 8500, a directx 8 card! (TRUFORM) The problem is that as it wasn't a standard then, it was barely used (Serious Sam and Return to castle wolfestein were two of a very low number of games that gave you the option to use it)
It should be used much more frequently in the future, as is exposed in directx11, and reciently in the newest 360 SDK, so games that use it in it's windows counterpart should use it in the X360 version, where you could use SPUs to do a similar function.







