Faster GPUs are always a good thing, though this looks like it's "only" clocked up 30%. I sort of have a hard time believing it's really faster than a 7950GTX-but maybe it really is in newer games. I bet it's slower in old games, but then again, I bet it's perfectly fine for older games.
The Geforce 8800 is supposedly launching in Q3, and while it's supposedly paired down in some way it only draws 22 watts, which obviously gives it the best power/performance ratio on the planet (actually the previous winner would be the current 8800s, even though they draw around 100 watts).
At any rate, I wouldn't worry too much about not getting this. Yeah, it's better than the 8600GT, but it's not like the kind of difference there was last year between the pathetic x1600 and the Geforce 7600GT/79x0 cards. I don't think anyone would be stopped from buying a Macbook by having a part that's 30% slower.