Amazon has started pushing out an over-the-air update that'll bring a slew of new features to its budget Kindle Fire tablet. Topping the list of upgrades is new sharing functionality that makes it possible for readers to send passages and notes from within the comfort of a book via social networks like Facebook and Twitter by highlighting and clicking "Share." Also on the slate is supplemental material powered by Shelfari, letting users find character descriptions, glossaries of of common terms, locations and author information from the comfort
