"Copying all those pages presents many difficulties, but writing software to make the books useful to searchers is even harder. “The scanning technology is boring,” Clancy said. “The real challenge is to get somebody something that they are actually interested in, inside a book. Web sites are part of a network, and that’s a significant part of how we rank sites in our search—how much other sites refer to the others.” But, he added, “Books are not part of a network. There is a huge research challenge, to understand the relationship between books.”
Fascinating story about Google’s effort to scan all the books in the WorldCat.