Here are some pages and prep work samples from an interactive book for the iPad I've been working on. Just waiting for the audio to be completed and integrated, then we'll be good to go!
Each page has interactive elements that relate to the story. These involve pre-rendered animations as well as real time 2D physics engine based simulations. I used Zbrush to create the characters and Photoshop to paint most everything else, with a little 3DSmax thrown in.