Books scanned as part of the joint project between Google and several universities, including the University of California Libraries, are now available through the Melvyl Catalog, some of them in full text.
For example, here is the result of a title search on berkeley history (this will open in a new window or tab).
Page through the results and you will see several items marked "Google Book Search", with a link to "More about this book", "Preview this book online", or "Read this book online." Depending on the copyright status of the book, Google will return a record view, a limited preview, a snippet, or a full text view. In some cases, cover art from book jackets is also shown.
Details on this and other scanning projects are available on the Frequently Asked Questions page.