Can anyone deduce what the DRM position is on books sold via Google Books? Closest I can get is http://books.google.com/help/ebooks/content.html http://books.g

Can anyone deduce what the DRM position is on books sold via Google Books? Closest I can get is http://books.google.com/help/ebooks/content.html http://books.google.com/help/ebooks/content.html which says PDF and ePUB formats that might have DRM in them -- but I wasn't aware there was any (significant) DRM in PDF format.