I updated the code in the repository... it turns out in the initial commit I missed some relevant files. As in, ALL of the relevant files. Oops. Anyway, it's fixed now.
I've also done some testing and made a video- it's working pretty well! When playing an 'A' on the piano (440 Hz nominal), the Pokey Watch hovered around 442 Hz (about 8 cents sharp), while the real tuner showed somewhat higher, maybe 14 cents sharp. I'd call that a win. This was with a 3-sample averaging filter applied to try to smooth the results. In the video, the LEDs correspond to within 21, 14, and 7 cents (outside->inside) from the nominal pitch. I think 15, 10, and 5 cents would be more helpful, but I want to make sure that kind of precision is at least semi-realistic before I start claiming as such.
Video here: http://youtu.be/ehbkRbINHs4