The Garmin has hardware in it that the iPhone does not which allows it to do those things, so if you wrote an app for the iphone to display the data, you'd still need another device to transmit, say, via Bluetooth to the iPhone. It would be easier for Garmin to adopt the iPhone features that it's missing rather than the other way around. I have a Tomtom that plays MP3s and makes phone calls when my cell is in BT range. If the Garmin had those features it would be able to do what you're looking for, I think...