This is a helper class for Google Maps v3, for highlighting areas of a
map by masking the rest of it with two polygons. The public API is the
same as google.maps.Polygon:

    var wyoming = [
        new google.maps.LatLng(45, -111),
        new google.maps.LatLng(45, -104),
        new google.maps.LatLng(41, -104),
        new google.maps.LatLng(41, -111)];

    new adammck.maps.Mask({
        "paths": [wyoming],
        "map": map
    });

Check out a demo at: http://adammck.github.com/gmaps-v3-mask/