Kindle Unswindle — how to remove the DRM from your purchased books…
This Kindle hack relies on a few Python scripts to remove the DRM from books already purchase via the Kindle Store. The scripts, of course, require Python to be installed; the hack also uses the Kindle for PC application so you’ll need to run this on a Windows machine.
Jacobsor sez, “This post provides a ‘how to’ guide for a simple way to remove DRM from Kindle, Nook and other ebook files using the open-source Calibre application in conjunction with some third-party plugins. I tried it on my Kindle library, and it works great, without needing to muck about manually with Python scripts. The Calibre program also allows you to convert files from one format to another, such as Kindle format (.mobi files) to epub files.”
http://apprenticealf.wordpress.com/2011/01/13/ebooks-formats-drm-and-you-—-a-guide-for-the-perplexed/