Apple Updates iBooks EULA 

Here’s the important bit:

[I]f the work is provided for a fee (including as part of any subscription-based product or service) and includes files in the .ibooks format generated using iBooks Author, the work may only be distributed through Apple, and such distribution will be subject to a separate written agreement with Apple (or an Apple affiliate or subsidiary); provided, however, that this restriction will not apply to the content of the work when distributed in a form that does not include files in the .ibooks format generated using iBooks Author. You retain all your rights in the content of your works, and you may distribute such content by any means when it does not include files in the .ibooks format generated by iBooks Author.

In short, Apple has rights to the .ibooks format, but not the content itself.