790i is now set to really make a name for itself, since it's the only chipset for Intel to really support the Core 2 range with any SLI support. NVIDIA has been very greedy with its SLI licensing to other chipset manufacturers. Since the GTX 200 series has finally landed, and its performance in SLI has proven to be good, 790i will go up in stock now.
MSI's version of the 790i differs from the reference design, which is nice. After all, if all the boards are going to be reference clones, there's no point in choosing a brand, just a board. The P7N2 Diamond is extremely powerful; its overclocking is impressive compared to the X48 chipset, but will it compare to a P45 chipset? - That we will have to see soon.
Overall, MSI has done a fantastic job, and the inclusion of a hardware sound controller is the best option ever for a high-end board.