Learning a language over Jabber/XMPP

The language learning app of mine is still under development, but I doubt I’ll be spending too much time on it until after my trip to America (and by extension, until after Christmas). In the meantime I’ve reading about XMPP, the protocol used by Google Talk and several others. One of the extensions that Google is largely responsible for Jingle which essentially allows voice communications. There are also a couple of XMPP clients written in PHP. So it may be possible to deliver lessons over XMPP through a chat bot.