Google Map With Overlay

<script type="text/javascript">
function show_map() {
    if (! GBrowserIsCompatible()) {
       alert("Oh Noes!  You can't play!  :-(");
       return;
    }

    var lat  = 51.244966;
    var lon  = -0.565678;
    var zoom = 14;
    var map  = new GMap2( document.getElementById("map") );
    var copy = new GCopyrightCollection("© ");

    // define copyright info for the overlay
    copy.addCopyright(
        new GCopyright(
            'Map Demo', 
            new GLatLngBounds(
                new GLatLng(-90,-180), 
                new GLatLng(90,180)
            ),
            0,
            '© 2009 Andy Wardley'
        )
    );

    // create a tiling layer
    var tiles        = new GTileLayer(copy);
    tiles.getTileUrl = function() { return "http://wardley.org/images/minipix/perl.gif"; };
    tiles.isPng      = function() { return false;};
    tiles.getOpacity = function() { return 0.5; }

    // create a map overlay to apply the tiling layer
    var overlay      = new GTileLayerOverlay(tiles);

    // show the map with the overlay
    map.setCenter(new GLatLng(lat, lon), zoom, G_SATELLITE_MAP);
    map.addOverlay(overlay);
}
</script>

<div id="map" style="width:600px; height:420px;">
</div>