Ever since I heard that the iPhone 3G would have GPS, I've been awaiting the launch of real 'turn by turn' navigation software. Tom Tom announced in June that they had the software running on an iPhone 3G, and since then... silence. Even googling 'Tom Tom +iphone' only brings up stories from months ago. What's going on? True turn-by-turn navigation (whether from Tom Tom or any other company) is for me and many others the 'killer app' for the iPhone 3G. I can't understand why it hasn't already been launched. Does anyone know why?