
One of the new features Apple rolled out with iPhone OS 3.0 was "find my phone." It works with MobileMe (formerly known as .Mac) to help you locate you phone on a map. It allows you to play a sound, to help you locate a nearby lost phone, and it even allows you to display a text message (even if the phone is locked) if you realize you've left the phone somewhere where someone will pick it up. It even allows you to remotely wipe your phone if it's stolen.
This past week an iPhone owner in Pittsburgh was robbed by two men who brandished a gun, and told him to turn over his phone, credit cards and PIN numbers. He complied, but later was able to log into MobileMe and provide the police with the current location of his phone; a Walmart parking lot. THe police confiscated the victim's property as well as that of several others.
If you haven't logged into MobileMe (and you have an account) and setup the find my iPhone feature, you might want to. Keep in mind that it uses the iPhones GPS tracking feature, which you must turn on in Settings. This works for iPod Touch too, assuming that the iPod Touch is in contact with a WiFi network.