A lot of people are speculating if Amazon came up with these terms or not.

From everything I can find (esp. this article - http://gizmodo.com/5388168/dont-get-too-excited-about-the-no...) the restrictions on Kindle lending are identical to the ones the Nook has (at least when it rolled out).

The B&N site for Nook currently states:

Exclusive LendMe™ Technology NOOK's exclusive LendMe™ technology lets you share favorite books with friends. LendMe™ books can be lent for up to 14 days. Just choose the book you want to share and send it to your friend's NOOK, computer, or handheld device enabled with NOOK software.

It sounds like the publishers are the ones setting the terms.