This article from Slate http://www.slate.com/id/2228109/  provides us a "glimpse into one of the device's greatest areas of promise: as a transportation tool. Rival smartphones, of course, are equipped with GPS, Internet access, etc., but none corral quite so many of the features that delight transpo geeks (an accelerometer, a compass, etc.) into one device. And rival phones can only envy the iPhone's flourishing app market, which includes some 65,000 options, many at least peripherally related to transportation (that is, if you include parallel parking games and the like).
It's intriguing to imagine how transportation itself could be changed by such apps". However, please do not forget that using your phone or texting while driving is illegal in some location and dangerous everywhere.