But your forgetting that you can always clock down a CPU. Read the 15"/17" PowerBook technotes and you'll see that they both can clock down to 612/765/815 Mhz (from 1/1.25/1.33Ghz) to save battery power, and the savings are excellent because it's a voltage reduction. Remember that IBM had estimated the 970 @ 1.2 Ghz running at 1.1v at 19 watts - half way to embedded and faster than what Motorola had for the embedded market in the same power range (the 1.06Ghz 7455 went as low as 15 watts iirc). So IBM is a process shrink away from the possibility of being more power efficient than the 7455 (although possibly not as efficient as the 7457). And if the rumor about IBM jumping directly to 60 nm instead of to 90 nm first, then they have the market, period (although I doubt this rumor is true).
