For me, I figure if you've already bought one of my books and you'd just enjoy the flexibility of being able to read it on your Kindle when you want, you should get it for free. So be one of the first to take advantage of the new MatchBook program. If you haven't read Sister WhoDat yet, get both versions for the price of the paperback (currently $8.96). The second book in the series is due out at the end of next month.
I'm impressed with the way Amazon keeps making book buying and publishing easier and easier for both readers and writers. It makes me wonder what else is in the works.