Other companies are jumping on the API bandwagon. ExLibris announced they have integrated a link to 'About this Book' pages on Google Book Search. From their press release:
Using a new “viewability” application programming interface (API) supported by Google Book Search, library patrons can now enhance their findings with Google Book Search features such as full text, book previews, cover thumbnails, and a mashup from Google Maps linking pages in a book describing a specific place to its location on the world map. Use of this “viewability” API has been added to the Ex Libris Primo® discovery and delivery solution, SFX® context-sensitive link resolver, and the Aleph® and Voyager® integrated library systems.
In the ILS world everyone plays follow the leader so the links should start appearing in all the other vendors products if they haven't already. Libraries have long had the ability to gather content in a similar manner (not full text) from Amazon.com. Many have done this successfully to augment (prettify) their catalogs, but the Google option will prove to be compelling both because of the potential breadth of content in the 'About the Book' package but also the limited commercial nature of the Google Book Program. The Google Book Program could become the primary distribution mechanism for publishers into libraries: Imagine every ILS using the Google API and publishers making their titles available via a subscription/lending module. All of this at very low capital expense for publishers.
The other interesting aspect of the Exlibris implementation is the integration with the SFX link resolver. How this will develop could also be interesting for the discovery of journals and articles.
Over on Exact Editions, Adam had some related thoughts on this.
Also, I had an additional thought that it may be Microsoft that has the better Publisher workbench/toolkit for managing access to their content from what I saw at their presentations last year. Where they are in their relationships to library intermediaries is anyone's guess however.