That same number is being bantered around many places. CNet quotes Digitimes ("the always breaking, not always credible Taiwanese tech news outlet"), MSNBC does the same.
AND YET,
Digitimes actually states that B&N "has
taken delivery of close to three million Nook Color e-book readers from its production partner, according to an estimate by sources from the Nook Color supply chain." (Italics mine.)
And that sales "of the Nook Color topped one million units in the North America in the fourth quarter of 2010 and reached 600,000-700,000 units a month during the January-February period of 2011."
So, the news outlets, in an on-going effort to be first rather than be right, aren't even reading the bloody unreliable source correctly. 1 million units sold in the 4th quarter of 2010, taken delivery of 3 million units (in a warehouse somewhere), and 650,000 units/month in Jan-Feb 2011, which works out to about 2 million in Q1 2011.