The idea that AMD was skipping DDR2 was a rumour, which AMD has denied in this article.
The Athlon X2 will come crashing down in price by the time socket M2 comes around, AMD is migrating the entire Athlon 64 line-up to dual core architechture, and most likely the FX series will also be manufactured as dualies by the time this happens, since multithreaded software should be most abundant, so the prices will drop.
I personally like XDR RAM better than DDR3 just because it has DDR3 speeds with latencies of DDR1, but as I've said, it's hard for any company, let alone an underdog like AMD, to push a new platform onto the market, especially if it's freaking expensive, and especially since the built in memory controller dictates one and only one type of memory.
Intel C2D E6320 / AMD Athlon X2 3800+
Gigabyte 965P DS3 / DFI nF4 Ultra-D
2GB OCZ Gold PC2-6400 / 2GB OCZ Gold PC4000
eVGA 8800GTS 320MB / eVGA 6800GS 256MB
150GB Raptor / 74GB Raptor
2x500GB / 320GB
OCZ GameXStreme 850w / OCZ StealthXStream 600w