Several people have started with millions of records from the Library of Congress, data from LibraryThing and digitized pages from real books from the Internet Archive and started The Open Library. Their goal: be the central place to go for book information.
In its present state, you can search among 12M records gathered from the Library of Congress, and whatever books are currently available from the Internet Archive, you can start reading away. This currently represents about 150,000 out-of-copyright books.
Now... what exactly *is* this? Just another catalog? Another place for digitized books? It seems they are trying to be a cross between all we've seen before: a Wiki'd Worldcat, Google Books, and the OPAC. (However, right now libraries would still have to keep their own OPACs).
A Wiki'd Worldcat? That's sure to rattle more than a few librarians. Worldcat is good, I think, because of the quality work librarians do; however, contributing data to it is only thru an "elite" group of librarians. It seems The Open Library wants to remove that barrier. I'm sure that's good, but also a bit dangerous. Will we, as librarians, also have to battle over which subject heading and LC class number is best, ala Wikipedia?