The first 1300MHz DDR2 memory modules will soon be available on the market. This is faster than DDR3 memory, which will start at 1066MHz but will also have 1333MHz memory 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.
The best thing about DDR3 is that it can do 1066MHz at 1.5 V and 1333 should work at similar voltage as well. AMD already said that it stays loyal to DDR 2 only, at least till the end of this year. DDR 3 is of course end up more expensive at least at the beginning but the price will drop eventually, just give it some time.
The first DDR3 memory modules will be available in the second quarter of this year, as Intel releases the G33 and P35 chipsets.