The issues are, of course, much more complex than they are being caricatured as in this thread. But, hey, it's fun to beat a straw man.
The basic issue isn't that Google books is good for authors or not (I think it is). It's can Google copy the entire book and use it for profit without the author's permission. It's a principle and a rather important principle. In a broad brush, it's the same reason that Rockefeller Plaza is closed to the public once a year. You have to actively maintain your rights to a property to keep it.
http://www.nytimes.com/2011/10/30/ny...ip-rights.html
In this particular case, it was found a case of fair use, though I suspect that it was more because the original judge felt that Google doing this was basically a greater good to the public at large. I happen to agree with that idea and I think that it is in the spirit of the rational for granting copyright and patents in the US Constitution, but it was no where near the slam dunk that some here assume. The fact that Google was using the work to generate a profit is normally considered of major importance in such cases.