A simple thought experiment is in order. Let's pretend that a Nook book (or any similar DRM'd ebook) could be lent in exactly the same manner as a physical book: to whomever you like, whenever you like, for as long as you like - with the added benefit of instantaneous, guaranteed, and toll-free shipping in both directions. This suggests that one could set up a library - a perfectly legal thing to do with physical books. The library (let's call it Cranny) would consist of an online service which automates the process of requesting a Nook book from anyone who owns a copy but isn't reading it at the moment. It would also allow you to send a request to recover any of the books you have lent out, with the same speed and ease. Consider: how many of the physical books on your shelves are you currently reading? In the course of any given hour? day? week? month? There is no reason to suppose that this situation would be any different for electronic books. The result: once a Nook book has been purchased by some critical number of Cranny users, just about all future readers would be able to enjoy it for free, with the aid of a vast global library. In fact, the entire process of pretending that a limited number of copies of a work exist (with the resulting need to ration access) becomes a farce. The Cranny scenario is clearly unacceptable to B&N, and (unsurprisingly) they have crippled the Nook's lending mechanism to prevent it - just as I predicted upon first hearing of the device. It turns out that a Nook purchase can only be lent once. Here is where things become interesting.
I believe that the Nook may very well relive the fate of Microsoft's Zune, which allowed users to exchange songs via a WiFi connection - with a play count strictly limited by DRM hardware, even under protest of the copyright owner (say, for files licensed under Creative Commons.) I cannot help but suspect that this ill-conceived anti-feature contributed to the Zune's unimpressive sales. A feature that is prominently crippled is worse than a nonexistent one, in that users are made vividly aware of frustrated possibilities - all the more so when the prohibited act is one which is entirely traditional with respect to the electronic medium's low-tech predecessor (whether it be CDs or dead trees.) The Nook's lending mechanism is an ill-conceived attempt to mimic the behavior of physical books - no doubt in hopes of persuading customers to pay a physical book's price for mere bits. The latter seems to be an incurable, lethal (witness NuvoMedia plus a parade of other corpses) obsession of ebook publishers.
My prediction: the best-case scenario from B&N's point of view would be that users simply forget that the lending mechanism exists at all. If, on the other hand, large numbers attempt to use it, waves of frustration will spread. The odiousness of a DRM restriction is not proportional to the absolute amount of freedom it removes; rather, it is a function of just how often and how painfully it thwarts a previously-commonplace (or otherwise natural) act which occurs regularly to most users (in this case, the dastardly deed of lending out a book more than once in its lifetime.) If DRM vendors were anything other than snake-oil hucksters, this fact would be common knowledge.
If DRM-crippled e-books were advertised as being exactly what they are - cheap, inferior, remotely-censorable imitations of actual books - their existence and growing popularity would not be a cause for concern. However, publishers understand that the freedoms traditionally enjoyed by book owners (such as the freedom to lend without restriction) will ultimately lead to the collapse of their business model - and so, they will persist indefinitely in their attempts to make water not wet. I invite the uninitiated to explore what the act of reading would look like were these freedoms to be lost entirely. (When the latter piece was written, the now-commonplace DRM-laden single-use textbooks were still a dystopian fantasy. Students - the perfect captive audience - are the canary in the copyright coal mine.)
Cross-posted at Loper OS.