title: jQuery .ajax() with jsonp not invoking success callback function
body: <p>I have a facebook iframe application that makes a cross domain request to my server and requests data in JSONP format. This is my client side code:</p>
  
  <pre><code>jQuery.ajax({
                  url: '***',
                  type: 'post',
                  data: {
                      method: 'set_user_prizes'
                  },
                  dataType: 'jsonp',
                  jsonp: false,
                  jsonpCallbackString: 'callback123',
                  success: function(data, textStatus, jqXHR){
                      console.log('success_function');
                      console.log(data);
                  }
  });
  </code></pre>
  
  <p>The problem is my success callback method isn't being invoked and I'm not sure why. Using Firebug I can see my server's response:</p>
  
  <pre><code>callback123({"success":true,"associated_prizes":[{"prizes_id":"6"},{"prizes_id":"1"}]})
  </code></pre>