My flight from ATL-DTW yesterday morning was oversold. You will get a message when you check in letting you know the flight is oversold and giving you the option to volunteer for a bump. No need to stand in line, nor even bother the GA. You can handle this at the kiosk now.
Funny how one person's "hit the jackpot" can be another person's annoyance! I'm glad that there are those who would find being bumped to be a good thing.
Also remember that many of us will same-day-confirm to a different flight, so even if the flight appears to be full, there may be DM/PM/GM seats that wind up open that day. (Personally, I SDC 75% or the time.)