On the Web site, there is an FAQ that explains how it works and how to sign up to give it a try. If I get an account, I'll post a story. But don't tell Steve Jobs! It's based on Flash! ;-)
Updated: Within an hour, my account was activated, and I created this sample. It was very easy to use, and as they add more clipart for creating stories, will be a great way to tell a story!
If you're in screen mode, you can right click to zoom in and out, and you can also click and drag the book to rotate around and view from different sides.
What story are you going to create?!