Using the volume rocker for scrolling/page turns sounds very Windows-ish -- reminds me of the old PDA days with Windows Mobile on it. While Windows Mobile was awful, Mobipocket Reader was great, and I think it allowed the user to employ volume controls in exactly this way, which I found very useful.
It's often a lot handier to flip pages in this way than having to touch the screen every time. Given Apple's dislike of hardware buttons, however, I wouldn't be surprised if Apple blocked this type of functionality on iOS devices.
