From the link - "Did you login with the facebook app on a smartphone while you were at the hospital? If so, they would have your GPS location at a certain time, when you later upload the photos from your camera, it would have a timestamp, and they could just look check where you had logged in from at that time."

If you are a home owner and this is true, you could possibly be identified -- say for instance posting from home 75% of the time and cross-referencing with certain demographic statistics collected from your browsing history and property records. Would that be legal?