I noticed on iOS6 when location services is on but no apps that use it are running, the arrow at the top right that indicates location services is on is not turned on. When I launch maps, yelp or something else that uses location services, the arrow indicator appears, once you close the app it goes away. Does that mean that location services is not running unless the app that needs it is active? If so leaving it on shouldn't drain the battery unless an app that uses it is running. Great news if true. I don't recall iOS5 working that way.