An interesting post from the blog of the Privacy Commissioner of Canada:
In the scenario described, the services used all have configurable settings about how much information to share to the public. Yet by mashing together a couple of services (iPhone & Flickr), some unanticipated consequences occurred. In this case, a reporter was able to track down a women he saw in a park simply because he observed her taking a picture with her iPhone.
For me, this shows the real challenge behind building technology that supports privacy. Society is still learning "the hard way" that when it comes to the Internet, you have to be very careful about your privacy. Even with configurable privacy settings, people may not realize the impact of linking services together.