The first Kindle active content titles are now available to Kindle customers. They are Shuffled Row and Every Word from Amazon Digital Services. We encourage you to download and try them at http://www.amazon.com/shuffledrow or http://www.amazon.com/everyword.

We continue to work with limited-beta developers who have been given early access to the KDK and appreciate your patience while we work towards opening up the program to more developers. Stay tuned.
Regards,

The KDK Team

Lo que viene a decir que en esas dos direcciones hay dos sendos libros con contenido hecho con el KDK, gratis de momento. Yo me los he bajado los dos. Uno de ellos es una especie de ir componiendo palabras con las letras que te dan. El otro no lo he probado.