In 2009, Sprint supplied phone location data to the FBI 8 million times: http://www.wired.com/threatlevel/2009/12/gps-data/

"The spokesman also said that law enforcement agents have to obtain a court order for the data, except in special emergency circumstances."

But:

"The US Department of Justice has petitioned the 3rd District Court of Appeals for the right to request cellphone location data without a warrant."

http://thenextweb.com/us/2010/02/11/dept-justice-pushes-warr...