If you're an iPhone or iPod touch owner, you can use the MobileMe Web site to locate your device if it's lost or stolen. You can also display a message on its screen, play a sound, or even remotely wipe all the device's data (to keep it private in case you're unable to retrieve the device). This feature is called Find My iPhone (for iPod touch owners, it's called Find My iPod touch, but I refer to it only as Find My iPhone in this section for simplicity).
Before you can use Find My iPhone, two prerequisites must be met:
Your iPhone must be updated to iPhone OS 3.0 or higher. If you haven't already done so, connect your iPhone to your computer, open iTunes, select your iPhone, and click Check for Update on the Summary tab.
You must ...