After selling 2.4 million Kindles in 2009, analysts surveyed by Bloomberg Businessweek predicted that Amazon might be able to double that number in 2010. But they more than tripled it, selling more than 8 million of the electronic-book readers, according to two anonymous sources "aware of the company's sales projections." (Amazon is famously tight-lipped about Kindle sales numbers.)

Amazon said in October that it's developing software that will let users read its e-books on Microsoft Corp.'s Windows Phone 7 mobile operating system. Consumers can also get Kindle books on the iPad, iPod Touch and iPhone, as well as on Research In Motion Ltd. BlackBerrys and phones running Google Inc.'s Android.

Amazon got its start more than a decade ago as an online book retailer. CEO Bezos said in an interview in July that the company began designing the Kindle in 2004 to ramp up sales of e-books.

U.S. sales of e-books are set to almost triple to $2.8 billion by 2015, according to Forrester Research Inc. in Cambridge, Massachusetts.

Read the full story at Bloomberg Businessweek.

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