As others have already mentioned, dual-core Atom processors have been out for 2 years, so a dual-core Atom is nothing new.
As regards the support of DDR3 memory, it's unlikely to make any measurable performance difference over DDR2 given the relatively anaemic CPU performance of the Atom. The reason is far more prosaic. DDR3 is now cheaper than DDR2 and that trend will continue so Intel are doing the right thing in moving the chipset support over to the less expensive memory. In a budget platform anything else would be foolish.