This is jabber.el, a Jabber client for Emacs.

jabber.el depends on GNU Emacs 21, in particular xml.el, and some
files from Gnus 5.10.  If you don't have Gnus 5.10 (M-x gnus-version
will tell), you can download sha1-el.el and hex-util.el from Gnus CVS
at http://quimby.gnus.org/cgi-bin/cvsweb.cgi/gnus/lisp/ .

To install, put all .el files somewhere in your load-path (or have
your load-path include the directory they're in) and put
(require 'jabber) in your .emacs file.  To install the Info
documentation, copy jabber.info to /usr/local/info and run
"install-info /usr/local/info/jabber.info".

To start using it, type M-x jabber-customize and set your username and
server.  Then, type M-x jabber-connect to connect (with prefix
argument, register new account) and M-x jabber-send-presence to send
presence (when asked for "show", an empty string means "online", and
the other choices can be found via tab completion).

Your roster is displayed in a buffer called *-jabber-*.  To
disconnect, type M-x jabber-disconnect.

For a less terse description, read the enclosed manual.

WWW: http://intellectronica.net/emacs-jabber