I got an email from Apple this morning pushing an enhanced version of the Game of Thrones. Basically the selling point seems to be enhanced maps, author's notes and illustrations. I suspect that this is similar to the enhanced Harry Potter books that one can get from Apple.
I can see where someone who became a fan of the TV series and has an iDevice might go in this direction. The books run $12 (the first one is $9). The downside is that this appears to be a iDevice specific book. I'm not sure it requires iBook, or if you can use it on a different reader if you strip out the DRM. An interesting experiment none the less.
I didn't find the right solution from the Internet.
3D Promotional Video Example