When we audit a bank, we talk with them about their smartphone controls - including asking about the use of remote wipe. Recently, I was thinking about the problem of when to decide that your phone is really lost or stolen and take the remote wipe plunge. You always think you might find the phone any minute now...
I've looked at Apple's Mobile Me service that offers a "Find My iPhone" service. Their service works well and offers a nice feature of being able to have the phone ring loudly even if you have the ringer turned off. However, since I didn't need the Mobile Me e-mail, contact, calendar syncing, the $99/year subscription fee seemed awfully steep for a location service.
I found a FoneHome app on the Apple app store that is an alternative to the $99/year subscription to Mobile Me if all you want is a way to track your lost phone. [more]
It's $1.99 on the store and allows you to track the phone (or phones) as long as it's online and GPS is turned on. It'll run in the background on a 3GS or 4 with iOS 4.
The app sends an update to the FoneHome website (via SSL) periodically, more frequently when you're on the move. You can log onto the website and see the last location it received as well as a history of locations reported. I suppose this could act as a poor man's teenager tracker as long as the kids don't uninstall the app or turn off their GPS…
The website is www.myfonehome.com. Once you setup an account (free), you can tie it to multiple iPhones.