Google are the best in the world at indexing information, they would definitely have the systems and people to make Google books a pretty incredible tool.
We have to remember, Google's goal "to organize the world's information and make it universally accessible and useful". (
http://www.google.com/corporate/)
They want to make everything available, including books, magazines, newspapers, legal documents. Basically they want to have everything available, and have the funds to fight the copyright battle vs over zealous publishers, so it should be an interesting few years.