that's not all, if you send a message to your iPhone 3G S, it will play an alert tone even if your ringing volume is off. SO if you misplace it and immediately notice it's gone, you can find it quickly.
Wow this is a totally cool feature I didn't know existed! I had no idea you could wipe out your stuff if someone snitched your phone. Thats super neat. The idea of finding it if its lost is kinda neat too - is it a special number you have to call or something?