I think I've gotten most of the blatant new wrinkles in Bookcase worked out, and so I'm putting out a pre-release version in case anyone would like to try the new features out or update the translations. I've got a few more things to polish up before I consider it Bookcase 0.7.
Among the new features are three new collection types: videos, music, and bibliographies. Improved import and export capabilities include Bibtex import, using Greg Ward's great btparse library, CSV import and export, and HTML export. Printing has been improved so that only the visible entries and columns are printed, rather than having a preferences option for that. Finally, if more than one field contains personal names, a pseudo-group for all the people is available for sorting and printing, meaning you can group by both author and editor, for example. There are other small things, and when I do version 0.7 for real, I'll try to list those as well.
One big question for anyone who tries this out is whether the btparse library compiles ok for you. I stripped it down to include it internally as a static library, but I probably made a mistake somewhere.
UPDATE: The XML DTD changed, so Bookcase 0.6.x won't be able to open files saved with version 0.7. Bear that in mind.