Concede means surrender or yield. So basicly if the opponent has total map control and your team is already about to rage quit anyway you can start a vote to give up. So instead of wasting 10 minutes on a boring game you can go on with the next map. It's like /skip but limited to the losing team in scrims.
Now that I am thinking about it a second time it's probably not worth the effort to code something like this. Probably will get abused anyway.

There is one more thing, not sure if it's a bug or I'm just doing it wrong:
If I do:
Code:
sv_mapcycle_timeout 0

in the init.txt then players get disconnected when the map is supposed to change. It happens while everyone sees the post carnage report.
At least with the gameservers.com UK server I setup right now.