Really? Because two days ago when this happened to me, I was chatting to a friend via Steam at the time this happened and we never lost connection in the slightest. Further more, after playing along with the message and I clicked OK to confirm that the servers have gone down and returned to Retribution's main menu, I just went back on public custom games and was presented with games already set up, waiting for people to join - and I did just that - joined them and went straight into my next game.
I always thought this seemed a little odd, I mean if it is going down for maintenance, it seems to be only down for ~5 seconds (if any at all) and doesn't seem to directly affect Steam itself. Regardless, I put up with it but then last night when I was waiting for a ranked match, someone posted in the chat box how they just had that message and got kicked back to the main menu - but yet, I didn't get the notification.
But it doesn't stop there, I've experienced this message while watching a replay! And again, I never lost connection to Steam at any point. Once I got kicked out of my replay, I just went straight back and loaded it up again with no problems.
So what's going on here? Is this a bug or what? People seem to be experiencing it at different times, I have never lost connection to Steam when it occurs, after getting kicked out of what ever game I'm in (even a replay!), I can just go straight back into a new game (or replay) without any issues. Surely if the servers went down, I shouldn't be able to continue playing online immediately after the notification.
Or is Steam just that efficient and well set out that Valve can organise their region specific server maintenance in a blink of an eye? I.:E immediately redirecting all users to other servers with no lag or re-connections needed. Although, if that really is the case, there still shouldn't be any reasons why I can get kicked from a local replay. I'm guessing that has something to do with the latest patches making the game think it's an on-line function, hence the removal of the pause feature.