There are some nice options iPhone owners to track their phones via GPS. AT&T has decided the join in on the game of phone tracking and has launched their FamilyMap service. The service basically allows the tracking of any number on your plan. This tracking isn't done by just cell tower triangulation, the plan actually accesses the phone's internal GPS to provide pin-point accuracy.
There is no visual notice on the phone besides the initial text message that the service is active so if you want to spy on your family just make sure to have the phone in hand to delete the txt really quick when you activate the service Every day personal privacy becomes harder to hold on to here in the US and AT&T has put another tool in the hands of the public to make privacy violation nice and easy.