Piano Staircase (thefuntheory.com)

For comments from the other times this was posted:

http://news.ycombinator.com/item?id=872759

http://news.ycombinator.com/item?id=873059

http://news.ycombinator.com/item?id=871721

A simple yet brilliant idea, but my worry is, Will adults let kids play on that staircase? :)