My iPhone 4 replaced my calendar, iPod, digital camera, and is the only thing I carry in addition to my wallet and keys. Google wants to do one better by letting you get rid of your wallet, too, eventually. There are limitations though. John Gruber explains:
But even by Googleâ€™s standards, this announcement seems very early. Itâ€™s â€œcoming soonâ€ to two cities (New York and San Francisco), on one phone (Nexus S 4G) on one carrier (Sprint).