Remember that NYC Taxi Commission data set that was used to identify strip club patrons and the comings and going of celebrities? Another data analyst has shown how it can be used to identify Muslim cab drivers. There's nothing wrong with being Muslim and driving a taxi, of course, but it does seem like a privacy issue. A person's religion and ethnicity is a private matter that only the individual should be able to reveal.
This shows, once again, the dangers of collecting and storing seemingly innocuous data. If you don't care about strip club patrons, how about religious freedom? And what was the rationale for collecting this taxi data again?