It's just a two-day event and won't affect total sales at all. It's unlikely that US Wii sales for December will be 2 million. In the first week of December they sold 240k, and by that time 4 million of the max 5.4 million quarterly production were already gone. Nintendo would basically have to supply 0 to Japan and Other for the remaining 3 weeks to hit 2 million in the US.
Given that Reggie mentioned US Thanksgiving as the one reason why the US got half of Wii shipments in November I think the US could receive a little less in December to equally accomodate Christmas in Europe and the New Year in Japan. Overall I could see US Wii sales for December (12/03 to 12/30) at 0.9 to 1.3 million.
Edit: The effect of these sales may also be quite difficult for ioi do estimate, right? Or does he have sources at the big retailers? Maybe Nintendo will put out a press info after the weekend, though I doubt they will so as not to piss off people who still won't have a Wii after that weekend.