For the past few years, Sony ( NYSE: SNE ) and others have been trying get mass adoption of ebooks. And with each effort, the question goes “is the world ready for ebooks?” The latest round: this week’s intro of the latest version of its Reader Digital Book and, with it, news that Sony and Borders are expanding their current relationship considerably. Borders has agreed to double the number of retail stores to more than 500 that sell the Reader and the two companies will launch a co-branded ebooks download store later this month, according to the Ann Arbor News. Another function of Borders’ and Sony’s partnership: joint lobbying of publishers to produce more ebooks. Initially, the online store will be a revamped version of Sony’s existing EBooks Connect site. Next year, the store will be tied to Borders’ new e-commerce site currently in beta. As Sony says in its release on the new Reader and retooled online store, It will offer more than 20,000 digitized books, including recent best sellers and classics. Some titles will carry a 20-to 30 percent discount off the regular store price. A number of publishers have just agreed to add their books to the Sony store, including Harcourt Trade, Pearson ( NYSE: PSO ) Education, Regnery Publishing, and W.W. Norton. Publishers already on board include Hachette Book Group USA, Harlequin, HarperCollins, Hyperion, McGraw Hill, Penguin Group, Random House and Simon & Schuster. For Sony, the hope is to find any way to drive interest in ebooks. For Ann Arbor, Mich.-based Borders, which the article points out has experienced two years of losses, teaming with Sony is part of the drive to avoid the fate of brick and mortar music sellers in the age of iTunes. With digital music sales dominated by Apple (NSDQ: AAPL), once considered to be a computer and software maker, Borders is trying to position itself early for the time when - or if - ebooks take off. -- DM News: Borders had an additional reason for signing on with Sony: its deal with Amazon (NSDQ: AMZN) expires in April 2008 and the Borders will sell books, music and movies on its own. Borders tried this before but, in 2001, the company struck the pact with Amazon.