"'Is a badge on Foursquare or a check-in worth your life?' That question, now commonly asked by the U.S. Army of its soldiers, is not rhetorical when even terrorists are taking advantage of geo-tagged data. For instance, when American military forces received a new fleet of AH-64 Apache helicopters at their base in Iraq, some deployed soldiers uploaded photographs of themselves in front of their new choppers to facebook. Unbeknownst to them, their phones had accidentally embedded their GPS coordinates in the photographs. Not only were insurgents monitoring the soldiers' Facebook postings, but they were also downloading the photographs and analyzing them for useful intelligence. The longitude and latitude information embedded in the photos allowed the terrorists to launch a series of precise mortar attacks that directly targeted and destroyed four of the newly arrived Apaches on the compound."
p. 143-144, Future Crimes. Marc Goodman