Google Book Search has added a new API, the Embedded Viewer API. In addition to being able to call for information about the book’s preview you can create static links to various parts of the book’s preview.
Additionally, Google has also come out with a way to embed the viewer into your webpage. They have a developer guide and a reference guide on how to use the embedded view API; and they created a Preview Wizard which does it for you automatically, that’s how I created this page. They have also provided some samples to help you get started.
You can see how this information, in conjunction with the book data API would come in handy if say you wanted to create your own catalog or use images in your already existing catalog.
Interesting side note: The libraries participating in the Google Book project have decided to work together to create something called the HathiTrust. This trust will keep all the books that Google is scanning in case Google goes belly up (Google provides an electronic copy of each book it scans to the library it scanned it from). They too are developing APIs and what not so that you can get data out of the books, it’ll be interesting to see what they do with all of this data.