Moving this discussion to the Adobe Digital Editions forum.
Adobe Digital Editions 2.0 works fine with Mac OS 10.8. I am running it sucessfully under Mac OS 10.8.2 at the moment. You can find more details regarding the system requirements at http://www.adobe.com/products/digital-editions/tech-specs.html.
Also, does anyone know why Adobe Digital Editions 2.0 does not allow me to print from it? It begins to look as if the pages are being printed and then stops half-way there. I have no idea where it even went. I was assuming it would be on my desktop, but since it never finishes, I am not sure what to do anymore. (Better add: trying to print it as an Adobe PDF!)
Many DRM books have printing forbidden as part of the rights.
ctrl-I while reading the book should give right information.