People do opt in. People outside of the tech game don't think of these as making themselves more vulnerable -- they only see convenience (or just blindly click

People do opt in. People outside of the tech game don't think of these as making themselves more vulnerable -- they only see convenience (or just blindly click yes to anything). I had a Twitter app (Tweetcaster?) that had a "show local tweets" option, and was amazed by how I could determine the individual dorm rooms tweets were coming from on a nearby college campus.