Another leak from the iBookstore has surfaced on Thursday and suggests Apple is stocking up on public domain books. The same hunt that reportedly found $10 bestsellers has found titles clearly taken from Project Gutenberg, whose goal is to post free versions of all non-copyrighted books online. The selection hasn't been counted by AppAdvice but could include all 30,000 titles and should have classics like Mark Twain's library as well as modern-day books from open-access advocates like Cory Doctorow, among others.