The option "Find my iPhone", will allow iPhone owners having a Mobile me account to locate their iPhone if they lost it, but also to remotely erase data on the handheld though the Mobile Me interface.The setup procedure is quite simple, you simply have to activate the option when adding a Mobile Me account on your iPhone, and then you will be able to locate it from the Mobile Me interface:
another interesting feature is to send a message to the iPhone:
Nevertheless, one will need to wait till June 19th to have such features available for all with the iPhone 3.0.