Thanks to the work of Regis Boudin, Bookcase is now part of the Debian GNU/Linux distribution. Some library symbol bugs were fixed, and a wishlist item has already popped up for spreadsheet import. I hope to have CSV import done for version 0.7.
UPDATE: Regis asked me to mention the help of Antonin Kral, who helped with the packaging and sponsored Bookcase into Debian. Very edifying to me to see Bookcase in there with such great software!