iPhones do have AVRCP (as of iphone 3G I think), the AVRCP allows basic functions like Next Track, Last Track, Play, Pause and some basic browsing. It is this AVRCP functionality that allows Track Skip/Pause of Pandora over BT when the source is "BTAudio". When the source is "Pandora" SPP (Serial Port Profile) is required for interface over BT. Apple iOS does not support SPP, iPhones will need to be wired and will not interface over BT. I think it is SPP that opens up the more advanced two-way communication allowing access to station lists, thumbs up and thumbs down.
Excellent point. It's probably been too long since that has been pointed out. For Pandora, Aha and other advanced playback, iPhones/Pods need to be "wired" and the App Connection needs to be also set to Wired. Of course, you'll still need BT pairing for phone calls.
I tend to forget this since I only use an iPod (wired) for my music library and everything else comes through my Android Nexus 5.