My Jabber/XMPP notification script forked from @kreneskyp
This script now also supports GTalk(Hangouts) and other multi-domain jabber services. If the server you connect to doesn't have the same host name as your JID, then use the "xmpp_notify_domain" setting. This will only work for as long as Google will support XMPP clients, which is currently unclear.
Peter's blog post: http://blogs.osuosl.org/kreneskyp/2009/06/02/irssi-notifications-via-xmpp/ links the original: http://staff.osuosl.org/~peter/myfiles/jabber-notify.pl
Side note: If you are using bitlbee or some other way that can possibly make the notification messages come back to you, you might want to put the notification sending JID on ignore to avoid a feedback loop.