In regards to verndewd's question about the timings. These timings represent memory latency settings, and are measurements in cpu clock cycles. This would be my only concern for AMD's DDR3 platform... If you compare memory bandwidth of socket 939 vs. am2, DDR1 @ 400MHz vs. AM2 w/ DDR2 @ 800MHz... You'll find that AM2 actually provide the SAME, or sometimes even less memory bandwidth, using any CPU clocked under 2.4GHz.
So on the low end (2.2GHz and below), DDR2 @ 800MHz actually gives LESS memory bandwidth than the same configuration on Socket939 w/ DDR1 @ 400MHz...
This is due to the fact that DDR2 has inherently higher latencies (CAS 4 and 5 latencies on DDR2 vs. CAS 2 and 3 on DDR1). Sinse these latencies are measured in CPU clock cycles, higher clocked processors are less effected by the latency bottleneck, so with a AMD 64 AM2 3800+ CPU @ 2.4GHz, you WILL find MORE memory bandwidth (~7.4GB/sec using DDR2 @ 800MHz & CAS4) vs. Socket939 (~6GB/sec using DDR1 @ 400MHz & CAS2), but using the same memory, and a slower processor (3200+), you'll find that DDR2 800MHz will render less memory badnwidth.
DDR3 will have even higher latencies than DDR2, so even if speed of the ram is higher (upto effectively 1600MHz), the latencies increased too, and you could be looking at little performance/bandwidth increases unless your using a CPU with a higher clock frequency (perhaps anything 2.6GHz and up)...
The moral of the story is, there are still some benefits to using a new generation of DDR on AMD platforms, but because of AMDs architecture of smaller caches than intel and lower clockspeeds, the performance benefit may only be marginal unless you make smart purchasing choices and opt for a CPU with higher clock-rate. On the other, greener, side of the coin, energy effciency should see a great benefit from switching to DDR3.
Anyways, this is all just speculation based on the transition from s939 to AM2.. Happy Building everyone.