I think it would be good if the iPhone had better privacy features so no one would have to worry when their friend asks to play around with it for a couple minutes, a question probably any iphone user has encountered a couple times. Here's a couple examples of how it could be useful: 1. I was just looking to get the app PokéDia, which I would use to jot down any thoughts/ideas I had through the day. But some of them, while not being private per se, might be a little bit strange to have someone else reading over. 2. Exercise logs/calorie counters. Again, not really private but a bit awkward for someone to tap into the app expecting your typical fart-level-entertainment app and then read about everything you ate that day/how much weight your trying to lose. 3. Mail. Could be useful for business men who don't want to have their iPhone ask them for a passcode every five minutes, but do want to keep sensitive emails on their phone without worrying. Same could be true for sensitive documents and the apps available that can edit them. I think it should be an optional feature the developer could add, and it could just show up in the apps preferences.