@khurtwilliams
I just found your article, very cool..
BTW I was wondering:
" Ideally, I would like a way to trigger the captures either via detecting the depression of the shutter button on the D40 or via a push button connected to the GPIO on the http://www.raspberrypi.org/."
Did you figure that part out? I worked out a way to do from my phone. (two years later haha).