Kindle 2 finally gets native PDF support, screen rotation
arstechnica.com/gadgets/2009/11/kindle-2-finally-gets-native-pdf-support-screen-rotation
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Companies that make the whole widget, like Apple, are able to nudge consumers towards buying new hardware by limiting the software features that work on older models. Amazon, which makes both the hardware and software for its Kindle e-book readers, appeared to be heading down the same path. The Kindle 2 had significantly improved system software that didn't work on the original model, and the wide-format Kindle DX came with its own, even more capable software stack. But now, half a year after the introduction of the DX, its smaller sibling is receiving a software makeover that will enable screen rotation and PDF reading.
The Kindle 2 hardware got a bump, as well, with a new battery that is claimed to have an 85 percent increase in life. According to Amazon, that means users can leave their wireless connection switched on and still get about a week's worth of use out of their device. Since the Kindle 2's battery isn't removable, though, anyone who already owns one is stuck with their current capacity.