Apple has announced the free iBooks Author, an OS X application for creating any type of ebook. As with Pages, a number of templates are available for authors to use to get started with making a book. With a tap, they can be filled with stock text. Elements such as audio and video can be dragged and dropped onto the page. Keynote slides and other widgets can be added as interactive elements, and glossaries can be created with the click of a mouse button. You can even instantly preview a book on the iPad via the USB sync cable.
iBooks Author is a free download in the Mac App Store.
It's not available yet, but should be within the next couple of hours. You can download it right now, if you have a Mac running OS X 10.7 Lion. We'll have a fuller look at it later on today.