Klint Finley, in Wired:
Now, thanks to a new initiative by the Internet Archive, you can click the name of the book and see a two-page preview of the cited work, so long as the citation specifies a page number. You can also borrow a digital copy of the book, so long as no else has checked it out, for two weeks—much the same way you’d borrow a book from your local library. (Some groups of authors and publishers have challenged the archive’s practice of allowing users to borrow unauthorized scanned books. The Internet Archive says it seeks to widen access to books in “balanced and respectful ways.”)
So far the Internet Archive has turned 130,000 references in Wikipedia entries in various languages into direct links to 50,000 books that the organization has scanned and made available to the public. The organization eventually hopes to allow users to view and borrow every book cited by Wikipedia, with the ultimate goal being to digitize every book ever published.