Heh, not sure where you're reading that from MicroBell... the article you linked says "Granite Bay's MCH... supports up to 4GB of dual-channel DDR". Boards based on this chipset have actually been out for quite a long time, since about a month or two before the Canterwoods and Springdales started showing up.
Edit: Did some reading about the motherboards supporting AMD's Opterons.. as far as I can tell most only (heh..) allow for up to 16gb of ram. I'm gonna see what else I can find...