Originally Posted by tompe
Yes, but maybe the intention was to put the work in public domain but since there is no tradition to say if the public domain book you are distributing here with you enhancement is copyrighted by you or in the public domain this information is missing.
Don't mistake public domain with Creative Commons. Public Domain are works which no longer have a valid copyright. Creative Commons (as used by Cory Dcotorow) gives me the right to download, format shift, and distribute. But in no way am I allowed to make any money on the work. That would be a violation of the license and copyright. With a PD work, I can allowed to take the work and reformat it how I want and I can even go and sell it.