The 2.3 software update for Amazon's eBook readers adds some new functionality to both the Kindle and Kindle DX. Below is a rundown of key improvements included.
Native PDF support: Unlike the Kindle DX, regular Kindles couldn't naturally display PDF documents before. The 2.3 update adds PDF support without the need for conversion. If you still wish to convert your PDFs to the proprietary Kindle format (which enables text reflow), simply send the PDF to your Kindle e-mail address (e.g. email@example.com) with the word "Convert" on the subject line.
Manual rotation: Pressing the "Text" key allows users to access the Kindle's "Screen Rotation" feature — quite handy for magnifying, say, PDF documents that don't have the text reflow capability (i.e. by choosing landscape mode). Users can choose one of four display options via the five-way controller. Note that Kindle Store pages can only be viewed in portrait mode.
Extended battery life: Consumers with the "Global Wireless" model of the Kindle (as opposed to the "U.S. Wireless" model) will see battery life last up to a week with the wireless feature on and up to two weeks with the wireless feature off.
Auto PDF file cropping: The margins of PDF documents are automatically cropped in landscape mode for magnified viewing.
Extended page view time: Screensaver mode comes on after 20 minutes instead of 5 minutes.
Note: DX users can also convert PDFs via e-mail the same way they can with the regular Kindle.