Android

"A far more effiecent (and accurate as they can collect a far greater set of data) system would be to collect it from GPS equipped mobile phones, and if they were to do that I could understand why people might get angry about the loss of privacy (although it could be opt-in and still probably kick streetviews ass)."

Android does this. When the device is first setup, you are asked whether to allow it and can toggle it in settings.