Even worse is those who used location on twitter or places on faceboook. That or the games like foursquare where you tell people where you are constantly
With some of the information i doubt it would be hard for a determined stalker to use your location data to track your movements and most likely predict them and of course if you mention your going somewhere at a set time...
Then of course if you wish to have some peace and quiet even if totally innocent or to buy a loved one a surprise etc, if they are used to tracking your every move wait until you switch it off
