schneier
The New York Times is reporting about a company called Securus Technologies that gives police the ability to track cell phone locations without a warrant:
The service can find the whereabouts of almost any cellphone in the country within seconds. It does this by going through a system typically used by marketers and other companies to get location data from major cellphone carriers, including AT&T, Sprint, T-Mobile and Verizon, documents show.
Another article.
Boing Boing post.