If the 3.0 software allows applications to control an accessory attached to the phone, does that mean we might see things like game controllers, keyboards, camera flashes, etc>?
I don't think we'll see any accessories that can be used in all apps such as a keyboard since that would probably require Apple integrating that into the OS. Most likely we'll see accessories that attach to the dock connector for specific apps... you'll need to be running an app that is specifically designed to work with the accessory. However, maybe they do have some sort of keyboard dock connector API in the 3.0 SDK... I haven't really looked at all the new APIs yet.