AjaxFancyBox.html

<div class="yourFancyBoxClass">
  {% if success %}
    <h2>It Worked!</h2>
  {% else %}
    <form action="{% url ajax_form %}">
      {% form %}
    </form>
   {% endif %}
</div>

AjaxFancyBox.js

$(".yourLaunchClass").fancybox({onComplete:function (){
        
  //grab this function so that we can pass it back to
  //`onComplete` of the new fancybox we're going to create
  var func = arguments.callee;
  
  //bind the submit of our new form
  $('.yourFancyBoxClass form').submit(function(){
    //this is strictly cosmetic
    $.fancybox.showActivity();
    
    var data = $(this).serialize();
    var url = $(this).attr('action')
    
    //post to the server and when we get a response, 
    //draw a new fancybox, and run this function on completion
    //so that we can bind the form and create a new fancybox on submit
    $.post(url, data, function(msg){$.fancybox({content:msg,onComplete:func})});
    return false;
    });
  }
});

AjaxFancyBox.py

def ajax_form(request):
    context = {}
    if request.method == "POST":
        form = myForm(request.POST)
        if form.is_valid():
            form.save()
            context['success'] = True
    else:
        form = WaitingListEntryForm()
    context['form'] = form
    return render_to_response("AjaxFancyBox.html", context, context_instance=RequestContext(request))