I've just exchanged some emails with Laurent Sansonetti about Alexandria and Bookcase. He's planning to include XML export functionality in Alexandria, and perhaps import capability for Bookcase XML files. Once his XML schema is finalized, I'm going to have an XSL transform ready so Bookcase can import Alexandria files. Improved interoperability between KDE and Gnome apps is always good!
He's also looking into z39.50 for Alexandria, so I pointed him to the Yaz library. My KIO slave has really languished, so he's likely to get to it before I will. I'm curious to see what his interface ends up looking like.