Full-scale integration of car sharing might be a long way off in America, but, now that the free Zipcar App for iPhone and iPod Touch is available, it's gotten one step closer. The app uses a Google Maps interface to provide information about available cars, and it's gotten mostly favorable coverage from Coolhunting and PSFK.Seeing as how most of our cars sit idle and empty of passengers for some 22 hours a day, and seeing as how pretty much the entire infrastructure of this country has been built with cars in mind, simplifying car sharing is a great idea. Anybody used it yet?