Google also announced this week that it now has the ability for authors to share info about their Google Books in circles on Google+, which should help with their sales and promos!

Google Books Product Manager Abe Murray says
Let’s say you are reading Alice’s Adventures in Wonderland, and you’d like your friends to read it with you (or you have a witty comment to let loose). Simply click on the Google+ Share box on the About the Book page or in a Google Books preview, enter your message, then select which circles you’d like to share details about the book with, and click ‘share’.
Sharing a book on Google+ will show its cover, the description and title, and links back to the About the Book page on Google Books. More info can be found at http://booksearch.blogspot.com/2011/...-literary.html