I have a new iPhone 3G and it does this strange thing which may be intentional. After I finish talking on the phone and pull the phone away from my ear it automatically hangs up. The screen just suddenly goes black.
Is that some function I can turn off? Or is my iPhone acting screwy? I can see how it might be convenient -- that you don't have to press the "disconnect" button when you pull the phone away from your ear -- but it's kind of annoying if you're just putting the phone down for a moment and intend to continue the conversation.