It's worth remembering that the DS was pretty bad in that first year, and didn't become a sales sensation until early 2006 with the introduction of the DS Lite. So that's not the most impressive milestone. In fact, we would hope a 3DS with both a (good!) Mario game and Mario Kart will be able to outsell a system that had neither.
Nintendo reported "more than 250,000" 3DS systems sold in the US in October, along with "nearly 180,000" DS units and "nearly 250,000" Wiis. Of course, all those numbers, along with every other game system's sales numbers, will go up significantly in the next two months. We'll have more NPD information this evening.