E-book sharing offers one of the more intriguing differences between the Amazon (NSDQ: AMZN) Kindle and the Nook from Barnes & Noble (NYSE: BKS)—and, it turns out, a chance for Jeff Bezos to critique the upstart. After telling an interviewer for the NYT magazine that he would stick to his company policy of “not talking about other companies,” Bezos walked right into a critique of Nook’s lending feature: “The current thing being talked about is extremely limited. You can lend to one friend. One time. You can’t pick two friends, not even serially, so once you’ve loaned one book to one friend, that’s it.” Then he (not too wisely) agreed that the decision could be compared to the life-and-death Sophie’s Choice. Amazon doesn’t allow lending but material can be shared between up to five devices on the same Kindle store account; also, not all Nook titles are part of the lending program.

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Much more interesting for e-reader wonks: Bezos says the company sells 48 copies of the Kindle edition for every 100 copies sold of the physical book, adding “it won’t be too long before we’re selling more electronic books than we are physical books.” That doesn’t provide any real clue about how many sales publishers are missing when they stick to physical only but it suggests to me that the risks are getting higher. Bezos also admits that Amazon uses print sales to gauge which digital titles to add; no further detail given but that may pertain most to efforts to try to add e-books of back titles.