haha, I could see this happening if minecraft updated, bukkit updated, but the shop plugin didn't. I'm sure EMC would be fine, but people would be a little inconvenienced--also people might get scammed through drop trading, and that would be no fun.
You would need a fish vault. I'm guessing this would be constructed with an array of some kind of container. Perhaps wooden in nature. Oh god, I don't even want to think about making a withdrawal
seriously though, I think I read on here that Justin rewrote the shop/rupee mod, so I imagine he wouldn't update the server until he made the mod compatible.
Hit the nail on the head apamment, Justin would make sure EMC is functioning before he made updated server available to the public.