Nov 10, 2011
We posted a youtube video just mere hours after we got the board in mostly working order. So far the video has being well even though we have not done any publicizing. Happy there is interest in the topic and people are enjoying our work.
Oct 28, 2011
When pressing several keys in the same column things don't work too well. According the people that make the button shield everything should work fine. We tried removing the diodes and things appear to work slightly better (although we don't know why). It's possible that the problem exists with the way that the button SPI code is implemented as it uses an interrupt without any sort of buffer. So if two button press were to occur between one cycle of the arduino a button press could be lost or mangled. As well we grabbed a large sheet of acrylic to make the case of the instrument. There was some concern about sturdiness, but hopefully the beefy 5.6mm thick acrylic should do it.
Oct 27, 2011
Played around with the LEDs today. Started using the Fast SPI  from google code and it seemed to alleviate the hardware serial receive issue. As well, put the 64 button shield not the arduino and everything seems to be a go. Wired in 7 buttons (with diodes) to test how things are going to work. Not too bad, however they delay between press in the button and audio playing on the iPad is quite substantial, perhaps 300ms. In order to see if the issue is with the iPad serial connection or just arduino latency I wired in a musical instrument shield from spark fun. Turns out the latency has something to do with the connection to the iPad as the audio form the shield appears to be almost instantaneus. Will need to do some more testing to see if the issue is the with the serial output, red park cable, or iPad external accessory api.