An incremental release for iBooks Author has been released with changes to the program's EULA. The update is 143.50 MB, which seems pretty hefty for a EULA change.
The change is an important one though, clarifying that Apple has rights over the format a book is in, not the content. If someone wants to charge a fee for an .ibooks formatted file, that document can only be sold or distributed through Apple, and that work will be subject to a separate agreement with Apple. The restriction does not include works distributed in non-.ibooks formats (such as the Kindle), as TUAW's Erica Sadun previously discussed.