From the article: "The app, which made its official debut Monday, offers a simple and straightforward ebook reading experience for all of your ePub files unencumbered by Digital Rights Management (DRM).
This includes most free ePub files available around the web, including those from Project Gutenberg, Tidbits’s Take Control Books, and Macworld’s own line of Superguides.
You may be able to open books downloaded from the iBookstore as well, depending on whether or not the publisher has decided to add DRM during the publishing process.
You can add multiple books to your Bookle library and browse each book's TOC through clicks or keyboard commands; actual books are laid out in scrollable form, like a website, with breaks for chapters and pages."
Via Robin Good