cross-site XmlHttpRequest in Firefox?

<script type="text/javascript" src="http://www.google.com/jsapi?key=your_google_api_key"></script>

<script type="text/javascript">google.load("maps", "2");</script>

<script type="text/javascript">
  function initialize() {
    var map = new google.maps.Map2(document.getElementById("map"));
    map.setCenter(new google.maps.LatLng(41.86, 87.68), 13);
  }
  google.setOnLoadCallback(initialize);
</script>