NY Times: When You Should (and Shouldn’t) Share Your Location Using a Smartphone by Brian X. Chen:
For years, tech companies have offered different ways for people to tell one another where they are. Yet all the popular location-sharing tools are limited or flawed, and in some cases broadcasting your location may not be worth the effort or worth draining your phone’s battery life. Even worse, location tracking raises numerous privacy concerns about who can snoop into your whereabouts.
Yet security experts agree that on smartphones, it is now practically impossible to stop location tracking. There is a multitude of ways for third parties to find out where we are, including cell towers, the metadata transmitted from telecommunications, and data logged on our phones.