I had earlier purchased another book, The Lightning Thief, and when I pulled it out of the iTunes library, all the files were there, but were encrypted. Having submitted my books to Kobo and flagged them to be DRM free, I then discovered that Kobo doesn't do DRM free yet. I was a little fearful of what would really happen in iTunes.
Luckily, my novel is DRM free, with only a little quirk. In the list view, in the Books section on the desktop iTunes, you can easily see in the Kind field, that just like the music, there are "Purchased" books and "Protected" books. The just plain "Books" are the ones I dropped into iTunes myself.
Just to make sure, I selected the book, command-clicked and duplicated it and pulled the duplicate to my desktop. Using the unzip -d work Pixie Dust.epub command I created an expanded copy. Inside, once I changed the permissions with chmod, I could read the text right out of the xhtml files with no problem.
So iBookstore will gladly sell DRM-free ebooks, if that's what the publisher requested.
UPDATE: I realized later I was getting too tech-y with my unzipping and stuff. This also works: Drag a "Purchased Book" out of iTunes into Calibre, click the view tab and read the book.