Today that changed. Kobo has unveiled a new ereader with a unique screen size. The Aura HD has a 6.8" E-ink screen with a resolution of 1440 by 1080. Not only is that the sharpest e-ink screen on the market, it is also a higher resolution screen than can be found on the Nook HD or any other 7" tablet. It looks like the Aura HD could ignite an ereader arms race as Amazons scrambles to release an ereader with a screen as sharp as the one on the Aura HD.