Yes. Helping users discover out-of-print books is one of the most important goals of Google Book Search. Even if your book is out of print, the traffic reports might prove to be helpful, shedding light on the book's potential. You will also earn money from ad clicks. Google Book Search can give you unique real-world insight into the popularity of an out-of-print book.
If you are self-published or if the rights to your book have reverted back to you, you can join the programme yourself and the book will be included in your Google Books account.
If you do not have a copy of the book to send us and cannot upload a PDF, tell us the names of the books that you would like added to your Google Books account, and if we scan them at a library they will be included in your Google Books account. Since we do not know when we will come across a specific book at one of our library partners, it is much faster to send us a copy or upload a PDF.