When you double press the Home button when on the 'lock screen' you get some play controls for whatever audio app is active in the background, or the Music app by default. On the iPhone running iOS 5 it also gives you a camera icon next to the "slide to unlock" slider. You can tap this to go directly to the camera app without having to unlock, find, and tap the camera app.
This camera feature is not present on the iPad, iOS 5 or not. You do get the other new camera features, a grid option, pinch to zoom, and the volume up button will snap a shot.