According to PhoneGap's documentation here http://docs.phonegap.com/en/2.3.0/cordova_inappbrowser_inappbrowser.md.html you should be able to get the url like this:
ref.addEventListener('loadstop', function() { alert('stop: ' + event.url); });
I don't believe you can access the url from the exit event but you could store it in a global variable during the loadstop event then view it in the exit event.