How can GPS applications make us feel more safe?

A member of my innovations team was taken at gunpoint by two men while she was parking in her grandmother's garage.  She was then taken by two men and held hostage in a deserted area of São Paulo for an hour, while one of the assailants drove off to an ATM machine with her card. The terrible incident made me realize that there is a tremendous opportunity for mobile operators, police officials and banks to collaborate in the development of GPS applications that could potentially minimize the risk of something like this happening.  I recently read an article in Wired about a service in the U.S. called SafetyNet, built to be used on the Android Platform. You select bad neighborhoods in the SafetyNet's map, so in case you end up in a sketchy part of town, your phone automatically switches into what they call 'watchdog mode'.  In case you feel threatened, you just shake the phone and an alarm goes off sending your location to friends and family.  It sounds like an interesting concept.  However, in a city like São Paulo where you can run into a dangerous situation practically anywhere, I'm sure the service would need to be redesigned.  

With the proliferation of location-aware phones, it's only a matter of time for someone to develop a killer application that can provide a better sense of safety.