As it has become known that iPhones are continuously tracking and recording one's geographic location, a few organizations have tried to make good use of this revelation, in particular by collecting, aggregating and visualizing these itineraries for anyone who wishes to share this data.
The latest visualization result made by Michael Kreil is remarkable due to its use of a nicely animated heatmap of sorts. In the movie, shown below (crank up the resolution!), the movements of 880 different iPhones in Europe have been analyzed for the month of April 2011.
The result looks like a hive of fireflies, pulsing in and out (to denote the loss of data during the night as phones tend to be turned off), and flying around, in and out of their favorite locations. The animations have been calculated based on real data, or by estimating the routes between known locations.