I've been running the 4.2 betas on my iPad for a few months, and updated to the GM 4.2.1 on Monday. Audio AirPlay worked fine (while video obviously didn't) up until the last beta. At that point, whenever I'd send audio to Apple TV, Apple TV wouldn't recognize it nor would it play any audio, while the iPad chugged along happily streaming the audio (track progressed, AirPlay icon was blue). I checked volume, tried changing tracks, rebooting and all that. I was hoping the problem would be fixed with this final release but it's not. Has anyone else experienced this problem? Edit: my Apple TV software is up to date as well.