Amazon’s Jeff Bezos has announced "[W]hile our hardcover sales continue to grow, the Kindle format has now overtaken the hardcover format. Amazon.com customers now purchase more Kindle books than hardcover books -- astonishing when you consider that we've been selling hardcover books for 15 years, and Kindle books for 33 months." In the past three months average, they’ve sold 143 Kindle ebooks for every 100 hardcovers. In the last month, it was 180 ebooks for every 100 hardcovers. The company has not released any specific figures about total Kindle sales or total ebooks sold.
Amazon also announced that five authors have already sold more than 500,000 Kindle books each. They are: Charlaine Harris, Stieg Larsson, Stephanie Meyer, James Patterson and Nora Roberts.
From the GalleyCat article at: