This is a project that I have worked on a few times, but never completed. I would still love to make something of it. I often find myself devoting time to this.
I saw in person a system like this at a trade show in Chicago. It is fascinating and I think that it can be done using the HiTechnic IRLink (yes, that again) with some remote control train motors or even standard remotely controlled PF motors. I would like to see several robot cells that each does something unique along with the system that connects them. This has the potential to be a massive system, and if anyone would like to devote a year or so to building a huge system, call me!
Skip ahead to about 0:48 to see the system in action.