Jeff B. brandishes the (endangered?) deviceCould the Kindle be in trouble? Sony released the third of its Kindle-challenging readers today, a $399, 7-inch wireless device called the Daily Edition. The new device won’t be sold until December and likely can’t yet compete with the Kindle in book selection, but early reviews indicate that Sony’s line of products is well-positioned to knock Amazon off its perch. Writes Andrew Nusca at ZDNet, “[I]t’s never more obvious that Amazon is up against a wall in the market segment it helped create.”The keys to Sony’s threat: First, lower prices. Sony’s low-end reader undercuts the cheapest Kindle by $100, and its top-end product, the Daily Edition, is $90 cheaper than the top-of-the-line Kindle DX. The second key is the open EPub format, which allows the files to be accessed by devices other than the Daily Edition. (By contrast, Amazon uses a file-type accessible only to Kindles.) Also, in a move that’s both good business and PR, Sony’s partnering with the New York Public Libraries, enabling users of the new device to check out books that disappear from their device a few weeks later. It’s the first time an e-reader can be used with a library. Writes PC World reviewer David Coursey:I hope Jeff Bezos will realize that his proprietary Kindle e-book format has “1970” written all over it. Maybe even “1965”. For e-books to catch on, as I believe they will, we need a common, open format for the books and less-expensive, even thinner hardware readers.Which is an excellent point. But while we’re on the subject, what year are warehouse robots?