As a follow up to the earlier message, I'm currently sorting our load issues (which is hugely related to the breakdown of our crappy web services installation which I have just disabled) and once we've confirmed with our hosting provider that things should be running ok, we should be back online.
Basically we had about 75 concurrent users on the mod manager at one time and due to some of our server processes not terminating correctly we had a backlog of processes still running which was eating at the CPU and eventually forced the server to become unresponsive. Since we've switched back to our default web services installation we shouldn't have this problem anymore.
We are also planning to move onto a new semi-dedicated server when we release RTB3 so we should have more uptime and everything should load faster too. I'm expecting RTB to be back online in a few hours, although I said that a few hours ago.