NYC Cab Flow Data

NYC Yellow Cabs have GPS fitted to them which have been tracked for the past year or so… anyway, there is an excellent article on this in the New York Times with obligatory map visualization:

http://www.nytimes.com/2010/04/03/nyregion/03icab.html
map (http://www.nytimes.com/interactive/2010/04/02/nyregion/taxi-map.html?ref=nyregion)

If we assume that taxi are the generally present in areas where people are, this could be a useful source of population mobility and certainly the sort of data which may be useful in real-time geodemographics.