It's called Google Print and is a new Google Beta. You probably know about Google's mission to OCR the world's greatest libraries (Harvard, Stanford, Oxford, NYPL, etc.). These e-Books are starting to appear in the SERPs (Search Engine Result Pages). Most of the books do not have full access, but its neat to see where Google is heading and the future of Goolge Print.

The command is:

book oliver twist
book alice in wonderland
book of mice and men

Give some of your favorites a try! I've only been able to locate a handful of classics. Please post some books you find in Google's database in this forum.