Google's Book Search program isn't exactly new but how many times have you used it? When I'm searching for something I usually just start with Google's default web search. If I'm looking for a book (or the contents of a book), well, I go to a bookseller's site.
Although it's hard to beat an in-person "flip test" with a book, Amazon's Search Inside the Book feature offers perhaps the best online alternative. But that's just one vendor and I don't believe Amazon has opened it up as a service to other websites. As of yesterday, Google is doing just that with their Book Search program -- here's the official announcement.
Whether or not this is significant depends on a couple of things including who adopts it and how flexible Google will be with the feature set. The announcement already talks about a number of websites that have either already implemented this service or plan to shortly. That's great news as it should enable each of those retailers to offer a Search Inside service like the one Amazon has enjoyed for many years now.
I'm more interested to see what non-retailers will do with this opportunity, including publishers. If this becomes a truly open system it could lend itself to all sorts of interesting implementations, beyond simple limited search access to 20% of the book. For example, what if publishers could create a subscription service that provides access to 100% of the book? That's where flexibility comes into play. As more websites implement this service Google will receive more requests to enhancement it.
In short, I love the idea and I'm anxious to see if it evolves into something much larger.