He's compiled a number of estimates over at Apple 2.0, with an average around the 3 million mark. On the low end of the range is 2.50 million units sold from Mike Abramsky of RBC Capital. Mark Moskowitz of J.P. Morgan is more optimistic with a projection of 3.75 million units sold.
Most were surprised by the sheer volume of sales. At one point, Apple was selling 45,000 iPads per day. Bernstein Research's Toni Sacconaghi considered what could happen if that "scorching pace" was maintained: "Apple could sell from 25 million to 42 million units in fiscal 2011, its first full year of sales...revenues would amount to about $15B, and likely grow about $10B [year over year]. This would make iPad revenues in their first full year nearly as large as Apple's current Mac ($18B) business."
Of course, it's unlikely that such a rate of sales could be maintained, even if the iPad has truly joined its smaller brethren in breaking out of the core Apple customer base. Sacconaghi estimates that 18 million iPads will be sold in fiscal year 2010.
Apple's Q3 financial conference call will take place on July 20th. We'll be live blogging it as usual.