From MIT Technology Review:
One of the optional extras that Twitter allows is for each tweet to be tagged with the user’s location data. That’s useful if you want people to know where you are or so that you can later remember where certain events took place. It also gives researchers a valuable tool for studying the geographical distribution of tweets in various ways.
But it also raises privacy issues, particularly when users are unaware, or forget that, their tweets are geotagged. Various celebrities are thought to have given away their home locations in this way. And in 2007, four Apache helicopters belonging to the US Army were destroyed by mortars in Iraq when insurgents worked out their location using geotagged images published by American soldiers.
My 2 cents? I think it’s important for developers to think through the privacy implications in their apps and provide an easy path for their users to protect themselves.