The examples given are cases where people fail to understand the implications of posting data to a public forum. A browser plugin is not going to magically make

The examples given are cases where people fail to understand the implications of posting data to a public forum. A browser plugin is not going to magically make people start thinking about the implications of their blabber-mouthing on Facebook. Another problem is lack of understanding of the privacy policy. Over the weekend I was talking with a family member who mentioned that she messaged something private on Facebook to a friend without realizing that it would be publicly visible. A plugin wouldn't have helped her one bit, she mistakenly assumed her conversation was being kept private by Facebook. She learned her lesson and now doesn't use that medium for that kind of information. Twitter's policy is that all of your posts are public (unless they are all private that is) which I think is less surprising to people.