Here’s how you could make it respond to drag and drop events using jquery. http://ssbits.wordpress.com/category/javascript-snippets/calendar/

gistfile1.txt

1. Make something draggable
$("#img_myimage").draggable({
    zIndex: 999,
    revert: true,      // will cause the event to go back to its
    revertDuration: 0  //  original position after the drag        
});

2. Make your calendar capable of accepting draggable objects (in the calendar setup)
droppable: true,

3. Add a call back method to your calendar to fire when something is dropped on it (in the calendar setup)
As an example, let’s just do an AJAX call to a page if the object is dropped on a date of today or in the future. Ignore else.
drop: function (date, allDay) {
    var now = new Date();
    var yesterday = new Date(now.getFullYear(), now.getMonth(), now.getDate() - 1);
    if (date > yesterday) {
        $("#dialog_somedivtagopensup").dialog("open");
        $.ajax({
            type: "GET",
            url: "SomeWebPage.aspx,
            cache: false,
            success: function (html) {
                $("#dialog_somedivtagopensup").html(html);
            }
        });
        return false;
    };
}

4. You could even add a bit to it, say you want to read something in later, like maybe distinguish between a couple of objects that have been dropped.
Let’s say you have 2 draggable objects.
$("#img_draggable1").data('taskname', 'Task1');
$("#img_draggable2").data('taskname', 'Task2');

In the drop function of the calendar object, you could check for this information.
var taskName = $(this).data('taskname');
if (taskName == "Task1") {
    //do something
} else {
    //do something else
};