Yeah, it could be limited to certain parts that have no other mcu components like I2C temperature sensors or anything. Also, since there are differences between the bottom lines of the manufacturers and sorting through the quagmire would be a pain, we could just accept the lowest end series. I think if we put too many limitations on it, it'd stifle creativity. I just really want to see what peoiple can make and a contest brings out the best in those kinds of things.
That being said, I'd still like to see what the lowest end chips can do so probably no more than 512 words of program and 24 bytes of ram. Maybe A/D could be excluded as well since the low end pics don't have it until the 22X series.
That project in the link is pretty cool. I was going to do something like that for my SLR as well but with some other features, and more parts. Very elegant.
Maybe if Dave is cool with it, he could mybe stir up some interest in the idea.