Puedes probar este código
<script src="http://maps.googleapis.com/maps/api/js"></script>
<script type="text/javascript" src="http://google-maps-utility-library-v3.googlecode.com/svn/trunk/infobox/src/infobox.js"></script>
<script>
function initialize()
{
var map;
var bounds = new google.maps.LatLngBounds();
var mapOptions = {
zoom: 10,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
map = new google.maps.Map(document.getElementById("mapDiv"), mapOptions);
var markers = [
['title-1', '<img style="width:100%;" src="canberra_hero_image.jpg"></img>', 51.508742, -0.120850, '<p> Hello - 1 </p>'],
['title-2', '<img style="width:100%;" src="canberra_hero_image.jpg"></img>', 51.508742, -0.420850, '<p> Hello - 2 </p>'],
['title-3', '<img style="width:100%;" src="canberra_hero_image.jpg"></img>', 51.508742, -0.720850, '<p> Hello - 3 </p>'],
['title-4', '<img style="width:100%;" src="canberra_hero_image.jpg"></img>', 51.508742, -1.020850, '<p> Hello - 4 </p>'],
['title-5', '<img style="width:100%;" src="canberra_hero_image.jpg"></img>', 51.508742, -1.320850, '<p> Hello - 5 </p>']
];
var infoWindow = new google.maps.InfoWindow(), marker, i;
var testMarker = [];
var status = [];
for( i = 0; i < markers.length; i++ )
{
var title = markers[i][0];
var loan = markers[i][1];
var lat = markers[i][2];
var long = markers[i][3];
var add = markers[i][4];
var iconGreen = 'img/greenMarker.png'; //green marker
var iconRed = 'img/redMarker.png'; //red marker
var infoWindowContent = loan + "\n" + placeId + add;
var position = new google.maps.LatLng(lat, long);
bounds.extend(position);
marker = new google.maps.Marker({
map: map,
title: title,
position: position,
icon: iconGreen
});
testMarker[i] = marker;
status[i] = 1;
google.maps.event.addListener(marker, 'click', ( function toggleBounce( i,status,testMarker)
{
return function()
{
infoWindow.setContent(markers[i][1]+markers[i][4]);
if( status[i] === 1 )
{
testMarker[i].setIcon(iconRed);
status[i] = 0;
}
for( var k = 0; k < markers.length ; k++ )
{
if(k != i)
{
testMarker[k].setIcon(iconGreen);
status[i] = 1;
}
}
infoWindow.open(map, testMarker[i]);
}
})( i,status,testMarker));
map.fitBounds(bounds);
}
var boundsListener = google.maps.event.addListener((map), 'bounds_changed', function(event)
{
this.setZoom(8);
google.maps.event.removeListener(boundsListener);
});
}
google.maps.event.addDomListener(window, 'load', initialize);
</script>
<div id="mapDiv" style="width:820px; height:300px"></div>