Interesting, I've been designing something that was going use xml-rpc but will look at jabber again. I need to build light, cross-platform perl-based servers for messaging between machines.

It is a little tangential but I'd like to mention there is also Ivy which is an interesting-looking, simple LGPL "software bus". Has anybody used it? I came across it a couple years ago through the Digistrips and Zinc sites (using perl to make prototype for air traffic control system in France).