Aya Karpinska has just published a piece for the iPhone and iPod Touch, Shadows Never Sleep. You can get it for free from the iTunes App Store - just search for it by title. Aya writes:

the piece uses a combinatory structure and the rhetoric of children's literature to tell the story of a restless shadow on a nighttime adventure. I describe it as a "zoom narrative" which takes advantage of the multi-touch interface of the iPhone and iPod Touch to allow readers to swipe their fingers across the screen and zoom in and out of images instead of turning pages.

There are Web-based demos and videos of the piece for those (like me) who lack iProducts. (Luckily, I did get to see Aya show off the piece at her MFA thesis reading this past May, and enjoyed it. Sure, I didn't rush out to buy an iPhone afterwards, but I'm stubborn.) The application is programmed by Nick Dalton; Roxanne Carter modeled to provide the shadow silhouettes.