You can read what you want into this special sale, but discounting certain e-ink Kindles to as low as $47 would seem to indicate that Amazon is starting to clear stock to make room for new models.
Alas, the 40 percent discount on "select Kindle devices and Kindle accessories" is only available to folks who are Amazon.com Rewards Visa Card holders, with the additional restriction of one promo code per customer (and yes, the usual disclaimer that limited quantities are available applies here).
Which Kindles are eligible for the sale? Just the entry-level non touch-screen models. The ad-supported Special Offers version sells for $79, whereas the ad-free version goes for $109. Take 40 percent off those numbers and you get $47 and $65, respectively.
If you had your eye on one of those pricey Kindle Lighted Leather covers (for any Kindle model), this might be the time to put it in the cart, because you can pick one up for $36 instead of $59.99. To reiterate, you need to pay with an Amazon.com Rewards Visa Card to get that discounted price and enter promo code KINDLE40 in the "Gift Cards & Promotional Codes" box at check out.
It's worth noting that sale only goes through August 15 (you can read what you want into that date), though it's quite possible that Amazon will offer cut-rate deals on refurbished Kindles as it has in the past.