Definitely unlimited

Well, Amazon have done it, just as the rumors suggested.

There is now a Kindle Lending Library.  Their announcement:

Today we are excited to introduce Kindle Unlimited--a new subscription service for readers in the U.S. and a new revenue opportunity for authors enrolled in KDP Select. With Kindle Unlimited, customers will be able to read as many book as they want from a library of over 600,000 titles. KDP authors and publishers who enroll their books with U.S. rights in KDP Select are automatically enrolled in Kindle Unlimited. Inclusion in Kindle Unlimited can help drive discovery of your book, and when your book is accessed and read past 10% you will earn a share of the KDP Select global fund. For the month of July we have added $800,000 to the KDP Select global fund bringing the total to $2 million.

To explain.  KDP Select is an optional program that makes your book exclusive to Kindle. This means that it cannot be made available on any other eBook site, such as Nook.  Up until now, only paid-up members of Amazon Prime were able to borrow KDP Select books. To compensate for lost royalties, Amazon set aside an amount of money every month, and this was divided among the authors whose books were borrowed.  It was rather like the lending schemes that are run in some countries, where the government sets aside an amount that is shared out at Christmas between local authors who have their books in public lending libraries.

So does this new development really provide a "new revenue opportunity" for authors?  Not really, in my opinion. Their books are now available to the general reader, and not just those who belong to Amazon Prime -- but that is not necessarily an advantage. More books will be borrowed, but the amount of money in the monthly fund is still capped, so the shares will simply be smaller.

That's the way it happens in the government schemes, anyway.