jquery-ui-dialog - How to hook into dialog close event

I have found it!

You can catch the close event using the following code:

 $('div#popup_content').on('dialogclose', function(event) {
     alert('closed');
 });

Obviously I can replace the alert with whatever I need to do.
Edit: As of Jquery 1.7, the bind() has become on()

I believe you can also do it while creating the dialog (copied from a project I did):

dialog = $('#dialog').dialog({
    modal: true,
    autoOpen: false,
    width: 700,
    height: 500,
    minWidth: 700,
    minHeight: 500,
    position: ["center", 200],
    close: CloseFunction,
    overlay: {
        opacity: 0.5,
        background: "black"
    }
});

Note close: CloseFunction