The Sirius XM Radio App doesn't natively support Airplay, but I found a workaround to get it working. The trick is to start airplaying a song from within the ipod app, then pause your song. Then switch back to the Siruis/XM Radio app and select a station and it should use the airplay session already opened via the ipod app. The only issue I've experienced is periodically the music skips on me when I get too far from my access point. My iphone is on wifi and my appletv is on a wired connection.