I’m not sure how I’ve missed this, but there are AirPlay controls in the Multitask bar under iOS 4.3. To find it, double-tap the Home button and then swipe left-to-right twice. You’ll see a volume slider and an AirPlay button.
Discovering unadvertised features like this is a big part of what makes using Apple products so much fun.
Update: Apparently it’s been in place since iOS 4.2. Call me observant.
[Via Dan Wineman]