I haven't played with my KIO slave for z39.50 access in several months. Apparently, it's broken for the most recent versions of yaz and yaz++. That doesn't really surprise me, it wasn't well coded in the first place. It was more of a proof of concept that I wanted to check. Before I stopped working on it, I'd removed the dependency on yaz++ in favor of direct use of yaz itself.
My plan is to get the final functionality in Bookcase that I want for a 1.0 release, and then to turn my attention to searching and data collection from the internet. That may take the form of z39.50 for books, along with Amazon.com and other book-sellers, IMDB for videos, FreeDB for CDs, and anything else I can grab. I've not put a lot of thought yet into how it all will work. Screen-scraping is a time-honored Internet tradition, but careful reading of some of the usage policies seems to indicate that it is "not allowed." IMDB seems to be real strict about that, for example. Of course, z3950 is the most versatile, for books.