From the press release:
Amazon.com is now selling more Kindle books than paperback books. Since the beginning of the year, for every 100 paperback books Amazon has sold, the Company has sold 115 Kindle books. Additionally, during this same time period the Company has sold three times as many Kindle books as hardcover books. This is across Amazon.com’s entire U.S. book business and includes sales of books where there is no Kindle edition. Free Kindle books are excluded and if included would make the numbers even higher.
The Company sold millions of third-generation Kindle devices with the new advanced paper-like Pearl e-ink display in the fourth quarter and the third-generation Kindle eclipsed “Harry Potter and the Deathly Hallows” as the bestselling product in Amazon’s history.
The U.S. Kindle Store now has more than 810,000 books including New Releases and 107 of 112 New York Times Bestsellers. Over 670,000 of these books are $9.99 or less, including 74 New York Times Bestsellers. Millions of free, out-of-copyright, pre-1923 books are also available to read on Kindle.