In a legal rewrite pushed out Friday, Apple has made its iBooks publishing agreement sound slightly less evil by clarifying just what you can do with the content you create on its iBook Author software.
Yes, all iBooks are locked to the iBook store but you can export those files as PDFs.
But there remain a few problems:
Another controversial piece of the user agreement still holds: Apple's right not to distribute your work if it doesn't like it. It's possible you could create a iBook that Apple then refuses to distribute in its store, the same way that it rejects certain apps.