By save do you mean persist to local storage?
You could modify the dragend event listener so that it updates the local storage with the latitude and longitude of the position the marker was dragged to. As this event is triggered whenever the marker is dragged, the local storage will always contain the location of the last drag (i.e. if the user drags the marker 4 times, local storage will hold the position of the fourth drag).
google.maps.event.addListener (marker, 'dragend', function (event)
{
var point = marker.getPosition();
map.panTo(point);
// save location to local storage
localStorage['lastLat'] = point.lat();
localStorage['lastLng'] = point.lng();
});
Obviously this would only work in browsers that have support for local storage so it would be wise to check for this before attempting to access the local storage