Well, they're moving towards Nvidia if you believe all you read:

The evidence has been mounting over the past weeks and now I can say with reasonable assuredness that future Apple notebooks, among other products, will likely have NVIDIA chipsets and graphics solutions in them come this fall.

I've been impressed with my experience with nvidia integrated graphics and not so much with Intel. If the MacBook gets Nvidia integrated, that's going to be really good news for casual 3D gamers. It's waaaay overdue; the mobile gaming tax to move to a MacBook Pro left a hole in the MacBook line.