Releasing datasets and preserving privacy
This is an old but thought provoking New York Times story describing how an AOL database of search results where names of searchers had been removed could still be used to track down a single individual by analysis of search terms. It points to the difficulty of identity blinding a database that may contain complex sources of information that provide hints at location.
http://www.nytimes.com/2006/08/09/technology/09aol.html?_r=2&oref=slogin