ninggadgettest.xml

<?xml version="1.0" encoding="UTF-8"?>
<Module>
  <ModulePrefs title="Hello, world!">
    <Require feature="opensocial-0.8"/>
  </ModulePrefs>
  <Content type="html"><![CDATA[
    <script type="text/javascript">
        function init() {
           document.getElementById("handler").innerHTML = "Hello, world.";
        }
        gadgets.util.registerOnLoadHandler(function() { init(); });
    </script>

    <div id="handler"></div>
    ]]></Content>
</Module>