So Google Print now has what is called "Public Domain Books" in its index. The Google blog calls this Preserving public domain books but many authors are really steaming about this. Try it out at http://print.google.com/.
Every page of these books is fully available online, so you can study, for instance, an illustrated version of Henry James' Daisy Miller (see page one, above) from Harvard's Henry James collection, or read how Private Joseph Taylor got his medal of honor in style, in The Seventh Regiment Rhode Island Volunteers in the Civil War, 1862-1865, from the University of Michigan.
And since every word is searchable, as you are browsing The Wealth and Biography of the Wealthy Citizens of the City of New York -- from the New York Public Library's collection -- you can find that there were more grocers than bankers listed in 1855.
This is a great asset for everyone, in my opinion.
At WebmasterWorld, they are discussing this and one member said that he searched on a book that was not in the "public domain." To his surprise he was asked to login to read more, the message read;
Why do I have to log in to see certain pages? Because many of the books in Google Print are still under copyright, you'll see a limited amount of these books. To help us enforce these limits, some pages are available only after you log in to an existing Google Account (such as a Gmail account) or create a new one. Other pages in each book are available without login. If you prefer not to log in but still want to see a few pages, click on the 'view an unrestricted page' link. Keep in mind that Google Print is about finding and discovering books, so you may not be able to see every page you want to.
So it searches parts of books outside of the public domain, also. Ben had me do a search on the world was so recent and up came the correct result One Hundred Years of Solitude by Gabriel Garcia Marquez.
Forum discussion currently at WebmasterWorld.