Kindle firmware, for Kindle 2 and DX, is being updated to version 2.3 today.
The update brings native PDF capabilities to Kindle 2, along with a landscape orientation mode.
I’m on a plane, so unable to download it right now. But you can see the new features, and member reactions, in this thread: http://www.kindleboards.com/index.php/topic,15964.0.html