From the New York Times review of the new Barnes and Noble Nook e-reader:
The “Lend Me” feature from the first Nook is still here, but it’s still laughably restrictive. You can lend a book only once, to one person, for two weeks, during which time you can’t read it. (You can’t read it while your loan offer is pending, either — another week.) You can lend only books whose publishers have agreed to it, and precious few have. Of this week’s 15 New York Times fiction best sellers, only two are lendable.