Holiday gifts of e-readers challenge publishing world

The latest USA TODAY's Best-Selling Books list, based on sales data from Dec. 26 to Jan. 1, shows a remarkable burst of digital book sales after e-readers were unwrapped as gifts -- for 42 of the top 50 titles, the e-book editions were the most popular format. The previous high, in July, was 25 of the top 50. One in five U.S. adults are reading e-books on a variety of devices, from dedicated e-readers to tablets (like the Kindle Fire) that can be used to download movies, music, video games and more. Forrester Research estimates that Amazon has sold 5 million Kindle Fires, priced at $199 each, since the device was released Nov. 14. Archrival Barnes & Noble has sold an estimated 2 million Nook Tablets ($249), released Nov. 17. Both devices are designed, in part, to compete with Apple's iPad (the latest versions are priced from $500 to $830), which sold about 40 million units last year. But even as the sales of e-books doubled from 10% of the overall market to 20% in 2011, print books still account for about 80% of the market. Overall print sales dropped about 9% in 2011. Read more here