Add status/more information to the server browser so that people know if a server is in a match or challenge race mode, so that they know what they're getting into... sticker-like labels next to servers might do the trick - red ones for 'In progress' and yellow for 'Intermission' perhaps?
Yellow/red sound like warning/error to me but I like that idea in general
Well, I think of red as being 'live', as per the light outside recording studios. I guess the other would be green, if going with that theme.