The unrelenting drive forward continues and iBooks is about to be hit by it. Soon any books published on a version of iBooks Author prior to version 2.2 will not meet iBooks requirements. So if you have existing publications make sure that you update iBooks Author to version 2.2 and republish them. You don’t have to do anything other than open your existing .iba files in the new version of iBooks Author and then publish the book. Submit the new .ibook file via iTunes Producer and you should be good to go.
Any submissions for Multi-Touch books to iBooks on or after 1 January 2015 must have been published with iBA 2.2 or later. Existing publications will still be available even if published with an earlier version of iBA.