I know I'm not really sure how the iPhone works, but I am signed up to a site called Alibia or something along those lines. Its a Chinese site for whole salers and one thing that keeps popping up is a iPhone replacement touchscreen. I do recall that the iPhone uses a multitouch panel, but it looks like its simply a plug with a adapter that plugs into a control board on the phone. Now my idea requires modding, but what if you can take apart the phone, make that connector on the board a dual type connection. One for the existing touch panel, then the other for the touch panel on the large screen. That way your doing a direct connection, minus the middle man. The only obstacle I can see is that the fact that its a multi touch type screen may be an issue, I don't know if it will work on a regular panel. Unless it uses a regular panel, and its the control board that actually makes it multi touch. There is also a chance maybe they now sell 7, 8 and what not sized multitouch panels, I can imagine if they did its so so expensive.