Lost IPHONE
iOS 4
Apple Event: May 7th at 7 am PT
iOS 4
What are you talking about? You don't have to "activate the app". You activate the service. Once you turn it on, don't turn it off.
The app is used to locate a different iOS device. Or, you can log into iCloud.com and locate it there... provided the phone is switched on, has not been wiped, and is connected to either the cellular data network or WiFi.
Lost IPHONE