In case you missed it Google Print Beta went live yesterday. You can find full info on the service here. At the moment you can search books from public libraries that are public domain, and there is a publisher programme to put books online. They hope to work on scanning copyrighted books, to enable searches and drive sales for books and downloads, but have some legal issues to work out, not surprisingly!
Microsoft are also set to digitize 100,000 books from the British Libraries 13 million books, at a cost of $2.5 million.