I'd like to see AirPlay enabled for streaming (at least music) from Mac to Device or Device to Device. Almost like turning a device into an AirPort Express. That way I could use my old iPhone 3g on a remote set of speakers and yet still have access to my entire library of music stored on my MBP. I used to be able to do something similar when Simplify still worked but the sound quality was lousy and you had to control it directly on the iPhone while it was docked. If AirPlay worked from Mac to Device, the sound would be much better and I could control everything from the Remote App on my current iPhone. I could always get another AirPort Express, but enabling it on devices seems like it would be a natural and useful update for AirPlay. Also it would allow you to stream the music to your yard or other places where you might not have an outlet readily available for the AirPort.