The recent settlement in the USA between Google and the Authors Guild and the Association of American Publishers is a landmark case. The final details have not been worked out but the settlement opens the way for online access to a vast array of books that are out of print but still in copyright. These will become available for full preview in Google Book Search and also for purchase by individuals. There will also be institutional subscriptions available which allow, for example, users of university libraries to have free access.
There will be a new Book Rights Registry created to search for copyright owners and distribute to them a share of the income from the new scheme.
Google Book Search also contains around 1 million titles that are out of copyright, works in the public domain that can be read in their entirety free of charge.