Empathy does XMPP/Jingle pretty well.The only free software client for Android that I know of which supports Jingle is Jitsi. And that is still in alpha stage.
Linphone which was suggested above is SIP. Jitsi supports SIP as well. Another great SIP client for Android is CSipSimple.
If you want only text chat then there are more free software XMPP clients for Android: Beem, Gibberbot, Xabber, Yaxim etc.
You can search the f-droid database to find free software Android apps: http://f-droid.org
