Verizon Wireless customers got a surprising message this month, as the company announced ambitious new changes to its Relevant Mobile Advertising program. The carrier already tracks its customers' locations as a way of generating valuable advertising data, but the new program goes further, following users' browsing habits so as to track them from their phones to their computers. It's a bold new step in the company's data collection efforts, allowing Verizon to build comprehensive profiles of each user while still technically avoiding any personally identifiable information.

The program works by seeding tracking cookies whenever a customer logs into the MyVerizon site, a typical tactic to follow a given user from page to page. In Verizon's case, that data is also combined with detailed data on each user's physical movements, taken every time the phone pings back to a cell tower for a signal. The result is a much fuller portrait than tracking cookies alone could provide. The end result is a tailored ad, delivered direct to your phone, representing a lucrative new profit stream for carriers at large.