"...we will be introducing lending for Kindle, a new feature that lets you loan your Kindle books to other Kindle device or Kindle app users. Each book can be lent once for a loan period of 14-days and the lender cannot read the book during the loan period. Additionally, not all e-books will be lendable - this is solely up to the publisher or rights holder, who determines which titles are enabled for lending.
Kindle To Enable Lending Soon
Interesting. You will be able to lend or read loaned books on your Kindle soon. With lots of restrictions for sure, but a welcome step nonetheless. This also introduces a way for Amazon to build more knowledge about its customers, specifically around their social networks. From the Kindle Community, Coming Soon for Kindle - kindle Discussion Forum