Awesome. I've got it up and running. I've been looking for a solution for the client/server distinction for a while. How much have you thought about the implementation of that?
The client watching references on the server is obviously more tricky. node.js already supports keep-alive by default. There probably needs to be some kind of chuncked reply mechanism that allows the server to send changes without the client having to send polling requests. Obviously, if the reference is not going to change frequently it might be cheaper to just poll every once in a while.