I read somewhere the upcoming socket AM3 CPUs will have memory controllers that will work with both DDR2 and DDR3.

meh? no. ddr3 is the key to next generation processors, pretty much across the board. AMD and intel have processors ready to roll, with memory controllers that can only work with ddr3. the longer it takes for ddr3 to become cheaper and mainstream, then the less motivation these companies have for releasing their ddr3 platforms. inel have already delayed lynnfield due to this. it would push back the whole roadmaps, next generation atom circa 2010 logical solution will have a IMC. without cheap ddr3 to go along with it, it cannot suceed as the current atom platform has.