The only way for Google, or any other service, to make books searchable is to index them.
Google isn't copying copyrighted books and then re-distributing them. The public never gets full access to anything. In my opinion copyright shouldn't even be an issue here.
My point is that the same concept applies to the internet as a whole. Search engines have to index (copy) it in order to make it searchable.
We can either completely cripple a useful tool (which is what the general consensus in this thread seems to be) thereby paving the way for the crippling of an even more useful tool (the internet) or we could... not.
We'll just have to wait for the courts to decide.