There is no difference in the chipset with the new revision, it is still Santa Rosa. The easiest way to tell which "revision" of MacBook Pro you have can be determined through System Profiler, you'll see "MacBookPro4,1" if you have Santa Rosa with a 45nm "Penryn" processor, "MacBookPro3,1" if you have Santa Rosa with 65nm Core 2 Duo CPU, etc.