DDR2 comes along for the ride.The Inquirer is reporting that ATI are currently working on a new chipset known as the RS485 to support AMD's next socket, the M2, which will support DDR2 memory.
The new board is supposed to come with single graphics support (dual to follow presumably) and will be pin for pin compatible with current South bridge chips (the SB450 and SB600).
This is all scheduled to arrive around Quarter 2 of 2006, but it will most likely take until the end of Q2/beginning of Q3 for a full variety of boards and CPU's based on the new socket to become available.
Article Link: ATI RS485 is AMD Socket M2 ready