AMD AM3 socket will support DDR3
 

AMD'S AM2 socket will "evolve" to AM2+ in Q3 2007. The AM2+ will include support for the latest greatest Hypertransport 3, scoring with 4.0 to 4.4 GT/s where the exact speed depends on the north bridge frequency.

The AM2+ CPUs are backward compatible with the existing AM2 CPUs and even the new AM2+ CPUs scheduled for 2007 announcement should work in the previous boards, but not at full speed.