The ASRock is not M2 already. There is a space for a daughter board which ASRock are thinking of making, they may not in the end. And ASRock make loads of motherboards. The board you are talking about is the ASRock 939DualSATA2 right?
The M2 socket should be released Spring next year or so. The reason AMD are going to DDR2, not DDR3, is that DDR2 has been around for some time, meaning prices have come down, and if they went DDR3, the factories would have to change, pushing up prices. The techniques for making DDR2 are also refined, giving increased performance.