Sebastian writes: "Index Data has just made its first release of a Z39.50 Server module for Perl. It provides a pretty simple API which hides most of the complexities of Z39.50 and network programming in general, so all you have to do is provide a bit of code to interface to your resource. You can draw on all the usual Perl tools to talk to back-end databases, create response records in XML, MARC, etc." Built using YAZ by the people who brought us YAZ to begin with... definitely worth a close look.