How does this help "end DRM"? The book was already in the public domain, so the only thing you did was to take a non-DRM'd copy and convert it into a proprietary format. Just because you can take a text file and convert it into .doc doesn't mean that you've "liberated" MS Word.

If you could take an e-book purchased at B&N and freely transfer it to your Kindle or vice versa, that would be the real end of DRM.

Here's an interesting question. Suppose you bought a book by a long-dead author in an e-book store, just for the sake of convenience, or maybe because Project Gutenberg doesn't have it yet. Then you decide that you want to read it on a different vendor's e-book reader, and it happens that some software can break your e-book's DRM. If you use this software, are you violating the DMCA even though the DRM is not protecting any copyrighted material?