With the new iPhone OS 3.0 update comes the ability to fine your misplaced iPhone and iPod Touch via Find My iPhone reports tidbits.

Find MY iPhone is a feature of iPhone OS 3.0 that requires a MobileMe account to operate and the service should work with both lost and stolen iPhones and iPod Touchs as there is an option which allows the owner to send a message on the handset or even erase all data.

To enable Find My iPhone you need to go to the Settings application which is hidden in the Mail, Contacts and Calendars section of your MobileMe account and the Find My Device item is located at the bottom, and simply turn it on. For the full rundown follow the link.