“Even though he was using an old computer running through the slow but anonymous Tor network, Andersen estimates he logged about 70 percent of all check-ins in San Francisco over the last three weeks. That amounts to 875,000 check-ins. Foursquare is one of the most popular of a growing number of services that let people quickly report to friends, family or the entire world where they are — and is part of a growing trend of making public more information that used to be private.”  (via White Hat Uses Foursquare Privacy Hole to Capture 875K Check-Ins | Threat Level )