DDR3 modules is all about less power

DDR2 is getting to 1300MHz. This is a super-overclocking of the Jedec specification but who cares, as the screened chips work that high. You have to tweak the voltage from 1.8 to 2.4v to make it work but 1300MHz can be done even with DDR 2.

Well, DDR 3 should start from 1066MHz but it will also have 1333MHz modules available at launch. This is what Intel next generation chipset wants from the memory, you need to match the FSB and memory to get the most out of it.