Iphones and ipads are being use by professional DJs right now. I think the pre needs an app too. I would love to see an app where user can design it's own interface of knobs, buttons, and faders. Then plug their phones in and have them send midi messages to programs lke ableton live or tracktor. If midi messages are too hard, simple sysex messages could be translated in bome's midi translator. I would be willng to assist in the development of such an app. I don't have any experience writng apps but I do understand what djs are looking for as far as a mid interface. Get in touch with me if anyone is interrested. Serously, I would pay good money or such an app.