Philipp Lennsen tells me that he thinks that Google's superfast "0.00" search results, previous post, were caused by a mistake that Google has now put right. So Google Book Search probably never was faster than the web search. Perhaps speed is not, after all, as important as extent or comprehensiveness.
In which context: Andrew Hodges' wonderful biography of Turing, reproduces a stunning passage, written by Turing in 1947, which prompts the suggestion that Google Book Search should be re-styled, or should aim to become, The Turing Library:
We could even imagine a computing machine that was made to work with a memory based on books. It would not be very easy but would be immensely preferable to the single long tape. Let us for the sake of argument suppose that the difficulties involved in using books as memory were overcome, that is to say mechanical devices for finding the right book and opening it at the right page, etc. etc. had been developed, imitating the use of human hands and eyes. ..[later].. In my opinion this problem of making a large memory available at reasonably short notice is much more important than that of doing operations such as multiplication at high speed.
LMS lecture quoted in Hodges Alan Turing: The Enigma of Intelligence p 319.
This passage does to a remarkable degree anticipate the methodology of building the Google Book Search system. Google have virtualised Turing's thought experiment. It is also fascinating that in this passage Turing considers that a 'library' (books) would be 'immensely preferable' to the abstract 'Turing machine' concept of an endless tape with which he had developed his mathematical and computational results. This paper of Turing's is fascinatingly parallel to, but more deeply digital than, Vannevar Bush's 'As We May Think'.
If Andrew Hodge's book were in Google's Book Search, I would link you to it straight away. It surely will be and perhaps this is one of the reasons why a Turing library is, indeed, immensely preferable to the endless Turing tape. The Turing library is actually coming to pass.