Is it art? Science? Or will it just be an inspiration for politicians to have a pefect surveillance tool? Wiki City Rome is a MIT project that gathers cellphone data (and of other wireless devices) to illustrate the movements of crowds and public transport vehicles in real time. Wiki City Rome is derived from MIT's SENSEable City Laboratory that studies the impact of new technologies on cities and may be considered science as well as art.

Though

Ratti's [senseable city lab's director] team obtains its data anonymously from cell phones, GPS devices on buses and taxis, and other wireless mobile devices. Data are made anonymous and aggregated from the beginning, so there are no implications for individual privacy.

I'm not sure if I'd like to be scanned by various detectors anytime and being visualized as small blue dot. But maybe that's just my paranoia. (Source)