Interesting project, but can you please use a better title in future? When the title is the same as the domain name, there's no indication of what is behind the link.

Perhaps something like "BeatBearing: arrange ball bearings on a grid to create rhythms"?

This is really cool. It seems like this would benefit from being built around a Raspberry Pi than an Arduino -- that way you could avoid the dependency on an external PC and expensive software -- and make the whole thing portable.