With the introduction of Bluetooth keyboard connectivity in iPhone OS 4.0, it's bound to happen: an accessory manufacturer will introduce a case with a slide out Bluetooth keyboard. This is why I think Apple will do it themselves and finally satisfy one of the biggest requests -- a physical keyboard -- while not forcing it into their minimalistic keyboard free design. The flat back of the leaked iPhone 4G is a clue to this. The rounded back of the latests generations would have added a lot of bulk to a case with a slide out keyboard. The flat iPhone 4G will allow for a flush keyboard that can be snapped right on to the back. If not intentional, the flat back of the new iPhone will make snap on keyboard manufacturers' life a lot easier. This is my prediction.