The (next) tipping point?
May 19th 2011. Mark this date down for posterity. From an Amazon Press Release:
Amazon began selling hardcover and paperback books in July 1995. Twelve years later in November 2007, Amazon introduced the revolutionary Kindle and began selling Kindle books. By July 2010, Kindle book sales had surpassed hardcover book sales, and six months later, Kindle books overtook paperback books to become the most popular format on Amazon.com. Today, less than four years after introducing Kindle books, Amazon.com customers are now purchasing more Kindle books than all print books – hardcover and paperback – combined.