I\'m looking into the new background location service options in the iPhone 4 SDK. It allows an app to run in the background and receive location updates from the device.
<
I've recently done some field testing of the new background location service to get an idea of what constitutes a significant location update, what kind of accuracy to expect for the location hits and our general experiences using it.
The results are detailed in a fairly lengthy blog post:
iPhone Background GPS: Accurate to 500 meters, not enough for foot traffic