Google Maps for Mobile has unveiled a pretty sweet new feature -- on a bevy of mobile phones, Google Maps is smart enough to figure out approximately where you are. Google's system uses a method known as tower triangulation -- your phone keeps a list of nearby towers, and makes note of how strong your signal is. Google accesses their database of towers and compares your signal strength and correlates it to a likely location on the map. It's pretty slick, and has been common in parts of Europe for ages. Location-based features of mobile phones are a killer app, to be sure.