This sounds like something you’d see on CSI:

A nine-year-old girl, allegedly kidnapped by her grandmother, has been found using a mobile phone signal and Google Street View.
A police officer and a firefighter in Athol, Massachusetts, joined forces after authorities were alerted that Natalie Maltais had been taken.
Officers used GPS in the girl’s mobile phone to find her approximate location.
They fed the co-ordinates into Google Street View, pinpointing a hotel where the child was subsequently found.
[…]
Since 2005, US law says that mobile phone providers must be able to locate 67% of callers within 100 metres and 95% of callers within 300 meters.
This requirement has led to GPS capability in most new mobile phones in the US.

The phone company has to cooperate with the police when there’s a missing person or when a life is in danger and in this case it ended well but I’m concerned about the invasion of privacy aspect of this, there’s the potential for abuse such as a widening of the scope of inquiry. I’m not thrilled that my movements can be monitored by a GPS system in my phone! That’s too much information available to be misused. I wonder if it’s time to switch to a prepaid phone 🙂
“He who gives up freedom for safety deserves neither.” Benjamin Franklin