I see that several of you are working on a novel and want to see iBooks Author have templates for novels. I'm also working on a novel, so I was hoping to see the same thing. I'm sure some more templates will be available soon, either through updates or third parties.
But I wanted to mention
Scrivener, a very under-appreciated program for writing novels. It's incredibly robust and has many writing tools you're not going to find in iBooks Author. Specifically, it has tools for helping with character development and storylines. iBooks Author is geared more toward education and interactive books. It might not be the best tool to write a novel in.
Plus, Scrivener allows you to export to both iBooks and Kindle, so you get to hit both markets.
I'm not ruling iBooks Author out though. Once I finish my book, I do plan on loading it into iBooks Author and experimenting to see if there are any creative interactive elements I can add to enhance my story. But I can't imagine writing a book within the software itself.
Hope this helps the aspiring authors here.