Apple snuck in a nice bonus in the iOS 4.2 update: now anyone can use the “Find My iPhone” feature without paying for a MobileMe account.
Find My iPhone, allows you to view the location of any iOS device from the iPad, iPod Touch, or iPhone. If you have a MobileMe account, you can also use the web-based locator.
The app lets you send a message to the device, so if anyone finds it, you can tell them how to get in touch with you.
If you suspect your phone is stolen, you can remotely wipe or lock all your data so the thief can’t access your contacts, photos, or other vital information like your current Angry Birds ranking.
If you are trying to locate an iPod Touch or wifi only iPad, the device must be turned on and connected to the Internet. You also need to download the app to each iOS device you plan on tracking.