We're not quite sure what sort of black magic it's worked to make it happen, but it looks like Amazon is really taking the art of firmware updates to a new level with the latest upgrade for the Kindle. Not only does it finally add native PDF support (which would have gotten folks rightly excited on its own), but it promises to boost battery life by a full 85 percent. That translates to about seven days of use with the wireless on, and is apparently the result of a six month firmware improvement and testing program -- can we get these folks working on other devices? Naturally, the latest firmware will be shipping on all new Kindles right away (just not the DX, it seems), and it will be pushed as a free update to existing Kindle 2s via Whispernet, although there's no ETA on that just yet.