I have an older ATV (160gb) version, so I can't use the airplay feature with my iphone 4. I am however wondering about this scenario. Tonight I was watching an HD rental on my ATV (rented on the ATV). I wanted to go into the bedroom to lie down. Could you use airplay to stream a rented movie from the ATV2 to an iOS 4.2 device? That would be a reason for me to upgrade I think.