It's possible that all three chips are now 65nm, or a mixture of 65nm and 80nm (TSMC's 80nm half-node process was used in ATI's R600 GPU). Needless to say, the chips are all smaller, which should yield some nice power savings.
Perla:
Playing Halo 3 on the new Falcon consumes less power than the old Xbox 360 just sitting idle at the dashboard.