Google has announced several very interesting updates to its Book Search tools, including an embeddable viewer for book previews and a data API. These should open-up a wide range of book-related applications. This follows-up on Google's release in March when they launched the first API for Google Book Search, the Book Viewability API.
Second, Google launched the Book Search Data API, which brings the functionality of its Data APIs to Book Search. The REST- and Atom-based API lets applications search for and get information about books and fetch data like reviews and labels (tags) from Google Books' My Library feature. Authentication is required for writing data back to a My Library collection, for which web-based applications can use AuthSub while ClientLogin support is supplied for stand-alone programs.
The last update is just a name change: Google has given that original Viewability API a new name, Book Search Dynamic Links. It allows developers to easily generate links to Book Search for any book that has a page or preview there, as well as display book cover thumbnail images in their pages.
To coincide with the API updates, Google has partnered with high-profile organizations like WorldCat, Goodreads, and the University of California's California Digital Library, all of which are now using embedded Book Search previews on their sites.