The Jabber::RPC::HTTPgate is an experimental package that allows you to bridge traditional (HTTP-based) XML-RPC calls and Jabber-RPC calls.
With the Jabber::RPC::HTTPgate module you can set up a gateway between HTTP-based and Jabber-based XML-RPC, so a Jabber-RPC requester can make calls to an HTTP-based responder, and vice versa.
See the module documentation for more details. There are lots of examples in the distribution.
http://www.pipetree.com/jabber/jrpc/httpgate/ is HTTPgate's home.