I also got the "iBook" ticket from the Apple approval police on two of my books. They are really firm about not to use that term.
This is especially interesting because Apple didn't do a good job to avoid any customer confusion in the first place. Right now there is a big mess. There are eBooks, Multi-Touch eBooks, ePub books Enhanced eBooks (which are not Multi-Touch Books). And there are Textbooks which are also Multi-Touch eBooks.
The application iBooks is for reading all of them. However the application "iBooks Author" doesn't author iBooks (those books don't exist), so shouldn't it be called "Multi-Touch eBooks Author". It was announced to create the new Textbooks. So shouldn't it be called "Textbook Author".
On the iBookstore, you can't search for those "Multi-Touch eBooks" aka "iBooks Authored books" or Textbooks. All those extra work from the authors and the bragging rights for Apple to differentiate them from standard Kindles and Nook books but nothing to search for them. Strange, isn't it.