This is a little project I've been working on for a while now, and I finally got everything working this past weekend. It's a "fully-networked, bus and token-ring enabled, 4-way scalable 'vectorization' of the Arduino" ... um ... or at least that's what this book tells me it is. :-)
This is what it looked like mid-assembly - you can see how I expoxied the 4 Arduinos back to back in a ring, and then placed DoubleTall ExtenderShields around it:
This is the finished project, including some blue LED vanity lights on the inside:
Another angle when it was first assembled:
And finally, here are some videos of it in action - enjoy!
Here's a link to the source code for the command dispatcher, and here's the source code for the nodes. If you're interested, I also have the whole thing up as a kit.