I am really curious about this. Mine is installed and partially working. I have power, radio works fine, blue tooth pairs almost immediately, the USB/30-pin cable _seems_ to be charging my phone, but the App Icon is greyed out and not functioning so I have no GPS even though all the proper Apps are installed on my iPhone4.
Tomorrow I will pull the radio and get rid of the Micro ByPass to see if that is causing the "communication" problem. I talked to a local installer today and he said that some Pioneer units are sensitive to the brake bypass and may not allow you to get to all menu opt