Presence Protocol (XMPP) that can be used to write Jabber-enabled applications.
For more informations about XMPP itself, see <http://xmpp.org/>.
The framework uses EtoileXML for parsing the XML streams of the XMPP protocol.
Etoile also includes a IM client named StepChat built on top of it.
WWW: http://www.etoile-project.org/