debian-mr-copyright-mode, that now provides an interactive function,
debian-mr-copyright-scan-filesthat shows which files are covered by which clause of the
debian/copyrightfile. I've also significantly improved my understanding of font lock and emacs lisp in general...
As a demonstration, the attached picture represents the results of
debian-mr-copyright-scan-files on the
monsterz source package (Sam's original example). The output clearly shows that some files are not covered yet...
You can get the emacs mode there. Its is starting to be good, but of course, many more improvements are still planned - in particular, quotes for files probably don't work yet. By the way,
imenu now works. A debian package should probably come soon.