up2gae.html

   <form method='POST' action='http://upload.example.com' enctype='multipart/form-data' id='form'>
        <input type='file' />
        <input type='submit' />
      </form>

      <script>
        var io = new goog.net.IframeIo;
        goog.events.listen (io, goog.net.EventType.COMPLETE,
        function (event) {
          alert(event.target.getResponseText ());
        });
        io.sendFromForm (goog.dom.$ ('form'));
      </script>