A few people have noticed that they have a few new pictures on their Kindle screensavers lately. And I noticed that I had a new version of the Kindle User's Guide in my library that appeared this week. It's all part of the new Kindle firmware update 2.3. Unlike previous updates, where Kindle owners had to guess and rely on other owners to determine what was included in an update, Amazon has created a 2.3 Firmware Update Highlights page for this update, which shows what the update includes for each of the Kindle versions out there (not including the original Kindle, which appears left out).
The major change is PDF support for the K2/K2i and the ability to rotate the screen. With this change, documents emailed to your Kindle email address will no longer automatically convert PDF files. So, Amazon has created a method of converting those PDF files that will work for DX users as well: just type "Convert" in the subject of the e-mail when you send a document for conversion.
The K2 and K2i also get improved battery life, while the KDX gets better PDF margin support and an extended period before the screensaver kicks in (20 minutes), which should help when studying, cooking or using a DX in meetings.
Those of us with the original Kindle are still on firmware version 1.2. I hope Amazon doesn't renege on it's promise to include us in the update next year that will allow better organization of content on the Kindle.