Amazon is laying out a huge number of updates today, including a spec-bumped Kindle Fire HDX 8.9 tablet and an all-new e-reader thats frankly amazing. But the most important update might be the one that technology enthusiasts are the most likely to dismiss: the lowly Kindle Fire HD. Amazon is releasing two versions (or more than a dozen, if you count the color, size, and kid-friendly variants), and they aim to redefine how consumers think of cheap Android tablets.