Heard about this last week at Computers in Libraries 2011 in DC amidst lots of discussion about ebooks. Google Books allows library users to preview books, find what they like and need, and access it in their library. This can be done through the “Find in a library” link which appears in each record in Google Books. For books in full view or preview, this list of links appears on the left-hand side of the screen; for snippet or no preview on the right side of the screen. When clicked on, this link runs a search for this volume in Worldcat, giving you the libraries closest to your location that have it in their collections. Of course, then users can click through to put the book on hold.
For those of you who missed James Crawford, Engineering Director, Google books at the conference, check out his talk. And also a great panel discussion of ebooks and Google books by Roy Tennant, Stephen Abram, Dick Kaser, and Marshall Breeding.