[NiLuJe]

@eboyhan: AFAICT, when referring to an amazon book with intact DRM, they're not keyed to the sha1 hash of the absolute path like DRM-free mobipocket books, but to their ASIN number.

And that's still true for books that've been handled by calibre at some point, so the asin number isn't in the filename anymore. So I'm assuming it's also in the metadata somewhere, and that calibre doesn't touch it, even if you change the title/author metadata.

Note that I didn't try this with a book downloaded directly on to the Kindle from Whispernet with the 2.5 fmw and the 'new' drm, so that may not be true anymore, but I didn't have any problem at all with my 'old' books, whether they were first downloaded to the kindle or a computer, and they're all handled by Calibre.