2.7 Kindles 2Q2011, Estimated over 25 million in 2011

Amazon sold about 2.7m of its Kindle e-readers in the second quarter as it took 51.7% of the e-reader market, IDC says. The second-larger share was taken by Barnes & Noble's reader, with 21.2%, in a market totalling 5.4m units in total for the quarter.

Source Gaurdian

Now let's talk other ereader numbers:

Digitimes has more information

6.9 million Kindles in 2010

Total 6.0 million Kindles in the 1st half of 2011 (not surprising, ereaders sell better in the 1st quarter than the 2nd quarter).

Expecting sales of 15 million 'new Kindles' and 'Kindle touch' (in 2011)
Plus some undisclosed number of K3s/'Kindle Keyboard' in the 2nd half of 2011.
And 4 million 'Kindle Fire'

Or: 25+ million Kindles in 2011 versus 6.9 million in 2010.

Look at that seasonality... 19 million in the 4th quarter versus 6 million in the first half of the year. Plus a few million more K3s sold in the 3rd quarter. :)

Amazon has laid down their cards. The competition must react.

Late edit:
IDC raised the ereader estimate from a mere 16.2 million units to 27 million. They're also going to count the 'Kindle Fire' as ereaders and not tablets. If they're doing that, I expect ereader sales to easily beat their expectations. Then again, they only expected ereaders under $100, not all the way down at $79. (I still am amazed how aggressive Amazon is being.)

If my previous post's prediction of new Kindles selling half as many books per Kindle as older Kindles holds true, we'll still see an explosion in ebook sales. I'm very much looking forward to seeing what indie author sales do after November 16th (new Kindle shipping date).

Got Popcorn,
Neil