Thanks for all the feedback. This was my entry in the Node knockout competition, along with @ollerac and @steadicat. This app was built using the awesome sockets.io library which made it simple to send realtime messages without dealing with cross-browser compatibility issues. Really the server's only job is to pass messages back and forth between the clients, who do all the work of detecting the formations and updating the other players when they move.
Really happy to see socket.io working for you guys. As someone mentioned, not only should it enable WebSocket for Firefox, but also IE6-8, iPad, iPhone, Android, WebOS, Safari 3, and others (even if connected through cross-domain)
Some other projects from the knockout leveraging it:
What I find amazing is how much fun people are having with it despite the fact that we had no idea what the game mechanics would be until the last minute.
We basically started with a board of pixels, and everything else just evolved through testing and laziness ("what's the simplest thing we can do to make the game slightly less pointless?").
