This example shows a static heatmap overlay for google maps. Please feel free to improve the layer implementation on github.
<!DOCTYPE html>
<html lang="en">
...
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
<div id="heatmapArea" />
<script type="text/javascript" src="heatmap.js"></script>
<script type="text/javascript" src="heatmap-gmaps.js"></script>
<script type="text/javascript">
window.onload = function(){
    // standard gmaps initialization
    var myLatlng = new google.maps.LatLng(48.3333, 16.35);
    // define map properties
    var myOptions = {
      zoom: 3,
      center: myLatlng,
      mapTypeId: google.maps.MapTypeId.ROADMAP,
      disableDefaultUI: false,
      scrollwheel: true,
      draggable: true,
      navigationControl: true,
      mapTypeControl: false,
      scaleControl: true,
      disableDoubleClickZoom: false
    };
    // we'll use the heatmapArea 
    var map = new google.maps.Map($("#heatmapArea")[0], myOptions);
    
    // let's create a heatmap-overlay
    // with heatmap config properties
    var heatmap = new HeatmapOverlay(map, {
        "radius":20,
        "visible":true, 
        "opacity":60
    });

    // here is our dataset
    // important: a datapoint now contains lat, lng and count property!
    var testData={
            max: 46,
            data: [{lat: 33.5363, lng:-117.044, count: 1},{lat: 33.5608, lng:-117.24, count: 1},{lat: 38, lng:-97, count: 1},{lat: 38.9358, lng:-77.1621, count: 1}]
    };

    // now we can set the data
    google.maps.event.addListenerOnce(map, "idle", function(){
        // this is important, because if you set the data set too early, the latlng/pixel projection doesn't work
        heatmap.setDataSet(testData);
    });

};
</script>
</html>

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