Neoseeker has published a combination review and comparison of DDR3 vs
DDR2.

Basically, as a simple example, if you had DDR2-667 memory with 5-5-5-15 timing, that would have exactly the same latency as DDR3-1333 memory with 10-10-10-30 timing, as the latency clock cycles had to go up to compensate for the higher transfer rates because there is no magic.

DDR3 is basically DDR2 with an extra level of interleaving on the memory modules, and just because it can clock out the data faster, it does not mean that they managed to increase the basic RAS, CAS and other latencies... and since they are now specified relative to a higher speed clock, the number of cycles for specifying latencies get larger.

DDR3 vs DDR2: Asus P5K3 and Corsair DDR3 1333MHz TWIN3X2048 Review