Ok, I think I may have found an undocumented feature of iOS 6 or some later release. I saw this while researching Pioneer's new WiFi Speakers (A1, A3 & A4). During the promotion video for the product line the actress is seen connecting to an Airplay device from the Music app on an iPad, no big secret there. But it's what she does next that has me scratching my head. The next sequence is of her increasing the volume, and assumingly broadcasting, to MULTIPLE Airplay speakers (three Pioneer speakers)! I've talked to someone who has iOS 6 developer version on their iPhone and they don't have this functionality. Does this look strange to anyone else? See attached pic. You can see the video for yourself on YouTube. The music player UI doesn't look familiar either, but I do see a Genius mix button in the pic, so likely native app? Notice the multiple checked radio buttons for the different speakers. In the video the individual volume sliders all move when she slides the master volume.