techboy,
I'm pleased to share it. The method behind the entire project is described here www.milibrodelasletras.com as well as a link to the code for the writing/drawing canvas (hint: it's the HTML5 canvas tag). Additionally, it has been added to Bob Bringhurst's free iPad app, DPS Tips, and finally included in the DPS cookbook.
One regret I have about the project is that it is difficult to find a place on the page titled "Juego" - where I have the letter matching game - to swipe to the final acknowledgents page. I think that many people never make it there, and that is where I provide links for all of the content creation.
Best,
Dan
