DJabberd is a high-performance, scalable, extensible Jabber/XMPP server
framework.  While it comes with an example server, it's really a set of
classes for you to build your own Jabber server without understanding
Jabber.  Instead of working with XML and protocol-specific details, you
subclass parts and work with sane objects and data structures and let
DJabberd do all the ugly work.

WWW: http://search.cpan.org/dist/DJabberd/