Amazon has launched a new service to augment its existing Amazon Prime subscription service this week that is sure to please ebook fans who happen to own a Kindle e-Reader. The new service dubbed the Kindle Owners’ Lending Library adds a free ebook renting option for Kindle devices.

The Kindle Owners’ Lending Library is a subscription service like the Amazon Prime Instant Video service, except that instead of videos, Amazon will let you rent one book from the lending library for free. And as long as you maintain the Prime membership, you can keep the book for as long as you need to finish it. Once you’re done, you are able to turn in the book and exchange it for another ebook. Another plus is that any highlighting and bookmarking done to the borrowed books will remain persistent across rentals, meaning if you ever re-borrow the book all of your markups will remain intact.

There are some caveats to the rental service, however. You may have noticed that I emphasized the term “lending library” when describing the service. I did this because (again, much like instant video rentals) the ebooks that you are allowed to rent will be from a smaller subset of the library of Kindle books that you are able to purchase outright. Amazon is looking to expand the library of books that you will be able to rent; however, in some respects book publishers can be more restrictive (and old fashioned) than members of the RIAA and MPAA are in allowing their content on subscription services. According to Tom’s Hardware, amazon is, in some cases, being required to buy a title outright from the publisher every time it is rented (!). The company has said that it is even going to these extremes to try and show publishers the benefits of incremental growth in audience and revenue that can be achieved with such a lending (subscription) service.

The other caveat is that Amazon is currently only offering free rentals to Prime members who own Kindles, meaning that users of the smartphone and Kindle PC applications are out of luck. Further, there are restrictions on the Prime accounts that are eligible. Naturally, a full Amazon Prime account is required, meaning that you must be the primary account holder to use this service. It is unclear at this point whether the discounted student versions of Prime will be able to use this service (I’ve hear conflicting reports where some are saying they’ve gotten it to worth and some people have reported that it is not working for them).

Despite the caveats listed above, should Amazon’s subscription service be a success (I think it will be), it will likely entice other platforms to adopt similar subscription services. Once Barnes and Noble, Sony, and Amazon all integrate some sort of subscription services, book publishers will (hopefully) be forced to make more content available. For now though, the Amazon juggernaut will have to brute force it’s way into a decent subscription library. If you are curious about the titles offered, you can see the selection here. There are a few top 100 bestseller books as well, and the library can only grow from here. Will you be checking out the new rental system with your Kindle?