As improbable as it seemed just a few years ago, e-book readers are at the top of many a wish list. In fact, in some cases getting your hands on one isn't all that easy. Although Sony and Amazon have been shipping e-book readers for years, new players are hitting the market, and promising emerging technologies are just around the corner. Is this a good time to say goodbye to books and buy an e-book reader? Probably, but first you should know what you're buying.