In "Google & Books: An Exchange," Paul N. Courant, Ann Kjellberg, J. D. McClatchy, Edward Mendelson, Margo Viscusi, Tappan Wilder et al. have commented on Robert Darnton's "Google & the Future of Books," and Darnton has replied.
Here's an excerpt:
[Darnton] Monopolies tend to charge monopoly prices. I agree that the parallel between the pricing of digital and periodical materials isn't perfect, but it is instructive. If the readers of a library become so attached to Google's database that they cannot do without it, the library will find it extremely difficult to resist stiff increases in the price for subscribing to it. As happened when the publishers of periodicals forced up their prices, the library may feel compelled to cover the increased cost by buying fewer books. Exorbitant pricing for Google's service could produce the same effect as the skyrocketing of periodical prices: reduced acquisitions of monographs, a further decline in monograph publishing by university presses, and fewer opportunities for young scholars to publish their research and get ahead in their careers.