...For reasons best known to themselves, Apple saw fit to include two graphics coprocessors in my Macbook, the 9400 and the 9600.
After just crossing the (small) pond from France to the US in a plane with no power in the seat, I'm glad they did. My 17" mbp lasted the entire 8 hrs thanks to using the wimpy graphics processor (and of course the LED screen).
Perhaps there is some other way to reduce power draw on the fast processor that could have duplicated this battery life without a second, slow processor, but I don't know what that would be.
So I for one am glad they did it.