It can be useful when I need quick info from the web fast. And as far as I know it only works while the car is stationary.If it's implemented, it would have to be over the cellular network (e.g. VZW, AT&T Wireless, etc.), not WIFI, which is not really designed for mobility and graceful/soft handover.
That question aside, why would you want full-time access to the Internet? It's another driver distraction we don't need with ever-increasing multi-tasking drivers, who pay more attention to the toys than the actual act of driving.