Amazon today announced a new program designed to woo publishers and authors to participate in the Kindle store and controversial Kindle Owners' Lending Library. The program, called KDP Select, will a feature a $6 million annual fund “dedicated to independent authors and publishers.” There’s a catch though—participating books and authors must give Amazon “at least” a 90-day period of exclusive access in the Kindle store.

According to an Amazon release, here’s how the program works: If an author or publisher selects the KDP option, and agrees to offer their books exclusively in the Kindle Store for “at least 90 days,” those books become eligible to be included in the Kindle Owners’ Lending Library, and can earn a share of the $6 million annual fund, which is apparently to be capped monthly at about $500,000. The monthly payment for each book is then based on that book’s share of the total number of borrows of all participating KDP books in the Kindle Owners’ Lending Library. For example, if total borrows of all participating KDP Select books are 100,000 in December (for which Amazon says the total monthly payout will be $500,000) and an author’s book is borrowed 1,500 times, they will earn $7,500 in additional royalties from KDP Select in December. Enrolled titles remain available for sale to any customer in the Kindle Store, and authors will continue to earn their regular royalties on those sales.

KDP Select launches today, with 31 of the top 50 KDP authors already enrolling 129 titles, including authors J. Carson Black, Gemma Halliday, J.A. Konrath, B.V. Larson, C.J. Lyons, Scott Nicholson, Julie Ortolon, Theresa Ragan, J.R. Rain and Patricia Ryan. Amazon officials say the fund will likely remain $6 million throughout 2012.

The program is the latest twist in Amazon’s controversial plan to create a lending library of e-books as an enticement for its Amazon Prime program. None of the major publishers are in the program and one executive at the Big Six observed the $6 million fund is equivalent to what they pay in advances on a weekly basis.