From Amazon news 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.
Engadget story links to full news release:
http://www.engadget.com/2011/01/27/a...in-sales-find/