Maybe I'm missing something here, but doesn't this sound like the old "solution in search of a problem?"

I mean, if you have the book in front of you, why would you need Google Book Search?

Seems to me that I could learn a lot more about the book, faster, by just thumbing through it.

Walt, I'm assuming the real use will much more likely be as a price comparison tool, which will increasingly turn the bricks-and-mortar bookshop into a showroom. See something you like the look of, pick it up off the shelf, scan the barcode and most likely find it cheaper online, order online with one click on your phone, put the book back on the shelf, go home and wait for it to turn up!

The reason this could be handy is, presumably, the same reason books contain a table of contents or index -- do you really want to thumb through the whole book to find a particular term or reference?

What if the book *has no index*?

Instead, scan the ISBN, enter your search term and be told exactly where it occurs in the book.

This sounds like precisely the right kind of application for a search engine, no?

This is not a special purpose application just for books search. It is one feature on a general purpose 1D / 2D barcode scanner, which can help comparison shopping, add contacts to your address book, trigger an sms, etc.