The beeb has an article up about using cell phone infrastructure to monitor (and thereby improve) congestion in Rome. The research is being done by a group at the MIT Media Lab - the same lab that I posted about a couple of days ago using cell phone for reality mining (though a different group). Max Kalehoff of BuzzMetrics commented on my previous post about Integrated Media Measurement Inc (IMMI) which appears to be using cell phones as the primary data gathering device for a number of different social/consumer measurements.
In contrast to the Reality Mining work, and that of IMMI, this research into Roman congestion uses signal information from cell towers. The insight being that signal strength fluctuates with the number of cell users in a cell in order to maintain good connectivity. The more people that enter a cell, the more power is required to support them. The Rome project also integrates a number of other social signals, for example, taxis with GPS.