Mindwalker released few weeks ago a coop mission in the
ArmA Underground forums.
Quote Mindwalker :
This is a cooperative escape and evade mission. Escape Chernarus at any cost.
You have quite the selection of spots for making your escape from Chernarus.
These spots are marked on the map, but be warned...
Not all spots will give you what you need, so you may end up looking for a bit.
Also... the Russians don't like you. So they WILL shoot you on sight... in the face.