Google Print is now publishing the full-text of public domain/out-of-copyright print works it has acquired through the Google Print library scanning project. The official Google Blog provides more information and examples of finding some of this material in this post.
The move comes a couple of days after it was announced that Google was resuming its library scanning project, which includes works that are in and out of copyright. Works that are in copyright are not reprinted online without explicit publisher approval.
Google book scanning still on hold from News.com has more follow up on the resumption of scanning, as well as how well-known quotes from some classic books fail to bring up these books in Google Print's top results.
Remember, some of this "public domain" material might not be available outside the US since Google is using different dates to determine copyright around the globe. It's pre-1922 for the U.S.
The same blog post also points out (in a postscript) that others have been digitizing public domain materials for years. Heck, Project Gutenberg has been around since 1973. This post includes a few comments from its founder, Michael Hart.
If you're looking for a one-stop shop for public domain books, I can't say enough good things about The Online Books Page from the University of Pennsylvania. It organizes and lists thousands of books (including Gutenberg content and now some Google Print content) from many digitization projects. It's amazing how much is added each day. Here's the "new listings" page that also offers an RSS feed.
Postscript: The British Library and MSN said the will work together to digitise around 100,000 out-of-copyright books for MSN Boook Search. More in the news release and this News.com story. About a week ago MSN joined the Open Content Alliance.
Postscript 2: Note to Google. I was reviewing a few public domain titles. How about a link to make the page larger? SITB offers this feature. Also, what about being able to access a page by page number after reviewing a table-of-contents or index?