I kind of started poking around at the backend protocol this morning. It's all websockets over HTTPS (very trendy stuff) and is hosted on EC2. I'm yet to dig much further than "let's see what this looks like in wireshark", but the behaviour and some of the errors I've observed in-game point to some kind of sync-every-now-and-then architecture. I wouldn't be surprised if it was really easy to do up a custom server for it.

I'm going to keep poking at this thing, so I'll document what I find here: https://gist.github.com/deoxxa/5111644 - feel free to join in!