I just released Bookcase 0.5. I'm rather happy with it. I have changed the DTD, so files saved from version 0.5 will be different than those from 0.4. If you care, backup your files, and don't use an old version of Bookcase to try to open newer files.
I added several fomatting options for printing, as well as the capability to select which fields get printed. You can also select which columsn to view in the list view by clicking on the header. Dragging the columns rearranges their order.
I haven't finished the feature for importing data from the Internet. Ultimately, I want to use a KIO slave, so I'm working on kio_z3950r, which will allow for powerful searches for the Library of Congress and other large librairies.