DDR2 support for AMD won't happen till atleast Q1 2006, if not H1 2006. It's not just mobo's that are involved, as AMD has the memory controller built right into the chips. Thus, an entirely new CPU design will be needed to support DDR2 on AMD's part. Roadmaps show that this will also involve a "new" socket type. For desktops, this will be the "M2" socket, which will have 940 connectors, and for Opterons, the socket will have 1200-some-odd connections.
Just google it, and you'll find everything you need to know. Just look for information that was published within the last month.