It's been revealed that the new 40GB PlayStation 3 features more than just a cut down hard disk drive. Sony has also thought to stick the 65nm version of the Cell inside the new console, reducing the power usage down to around 135 Watts (down from 200 Watts.)
Sony also jiggled around a few other components by making the heat pipe smaller, swapping out the motherboard for a new version, and added a button battery to keep time when the system is off. http://www.engadget.com/2007/10/30/4...r-consumption/