Best in class fraud detection vendors track various parameters of a transaction viz. the geo- location , device id, credit card eligibility of the consumer involved, etc. and try to identify a possible fraud, if any.

FORBES: Online fraud takes a new lucrative tack

Using 100 volunteers armed with Series 60 phones (like the Nokia 6682, pictured), the Nokia-funded project tracked such data as incoming and outgoing calls, Bluetooth activity, and approximate location (via celltower ID data).

ENGADGET: MIT project uses cellphone data to predict activities

Upgrades to the SpareOnePlus include a location-based service which identifies the exact location of the cell ID, accessible through a free smartphone app, as well as audible numeric feedback which reads the number dialed and incoming calls aloud.

ENGADGET: SpareOnePlus adds location tracking, audio alerts, keeps the 15-year life on a single AA battery eyes-on

People can now check in for a domestic flight from any location, and they simply show their photo ID at the gate as they board the plane.

FORBES: Fact and Comment

Sensor proponents, however, argue that smartphones and corporate ID badges already can transmit their owner's location.

WSJ: Tracking Sensors Invade the Workplace