var bounds = new google.maps.LatLngBounds();
var i;
// The Bermuda Triangle
var polygonCoords = [
new google.maps.LatLng(25.774252, -80.190262),
new google.maps.LatLng(18.466465, -66.118292),
new google.maps.LatLng(32.321384, -64.757370),
new google.maps.LatLng(25.774252, -80.190262)
];
for (i = 0; i < polygonCoords.length; i++) {
bounds.extend(polygonCoords[i]);
}
/// alert the center
alert(bounds.getCenter()); //the center is polygon center