Yup. That's why you should always have local copies.
I've been creating a DVD of all the books I've purchased/downloaded. It's all set up as a website with links and descriptions of what everything is. Whenever I update the (local) website with a few books, I bump the minor version number, and burn a new ISO.
I decide to put the effort into cracking all my DRM-encumbered, I'll be able to breath a sigh of relief.
Took about 10 seconds to find a python script that will extract the key used to encrypt nook books, and decrypt the books. Awesome. I'll be converting all my books to DRM-Free versions tonight!