Apple has announced the free iBooks Author which would be an OS X application for creating any type of ebook.
As with Pages, a number of templates will be available for authors to use for making a book. With a tap, authors can be filled with stock text.
Elements such as audio and video can be dragged and dropped onto the page. Keynote can slide and other widgets can be added as interactive elements. You can create glossaries with just a simple click. The feature of instant preview is available where a book can be seen on the iPad via the USB sync cable.
With iBooks Author, interactive books can be made for the iPad.
iBooks Author is available here.