According to the Kindle Matchbook page Amazon has around 74 thousand titles available as part of this program, including works from HarperCollins, Macmillan, Houghton Mifflin Harcourt, Amazon Publishing, Wiley, Chronicle Books, and Marvel.
This is rather a small figure compared to the 2.2 million titles listed in the Kindle Store, or even the more than 350,000 available in the Kindle Owner's Lending Library. Also, most of the publishers have only a limited number of titles, but HarperCollins is the exception. Amazon is showing over 9 thousand HC titles in the Matchbook listings, including some titles published in the past few months. Not so coincidentally HC is also the single biggest contributor to the Oyster and Scribd ebook subscription services.
Still, 74 thousand is a major improvement on the 10,000 title catalog that Amazon promised when they announced the program last month.
How the service works is pretty simple. Simply visit the Kindle Matchbook page and click the button, and Amazon will trawl your purchase history for compatible titles. They will be listed automatically.
Or at least that is the way the system is supposed to work. I tried it and it turns out that I haven't purchased any compatible books from Amazon, much to my surprise.
Have you tried it, and did you find any good deals?