Unmasking Social-Network Users

This article talks about how even though social networks promise to remove "personally identifying information" before sharing data with advertisers it is still fairly easy to identify individuals with that info. The article goes on to say that there online privacy is not realistic and how privacy laws should be changed because of it.
http://www.technologyreview.com/web/22593/page1/

This brings up an interesting topic in that we always think about one edge connecting two nodes; but what if there are more than one edges between the two nodes? as demonstrated by this article, even though some edges carrying confidential information should have been eliminated, ultimately it wasnt due to the fact that there must have been more edges for one node to get information regarding the other node. This also brings to attention that some social networks overlap. We keep thinking about social networks as one graph on a planar level with regards to one topic/connection, but what if the social network is made up of more than one social networks? We would be in the 3D level, with a whole new way of connecting nodes.