Note that a few admins have access to the console (Interface on the server computer that controls the server), which can enable them to upload a different version of the game and play that. Not sure if they are running bukkit, so it could be a different situation but still the same concept. Always things like LogMeIn or one of the mod/admins to be a close friend to the owner where its as simple as having a house key. This is my full guess, my hope is that they'd post that they are shutting down, this was a nice server with nice people running it, they'd at least notify us before turning their backs on us.