Blake has released a coop mission for ArmA2 in the BI forums.

Quote Blake :
Chedaki insurgents have raided your home village, Olsha, murdering several villagers. The rest of the inhabitants have fled to the hills except a few old women refusing to escape.
Later rallied by the village priest the men have scavenged some old weapons and are now ready give some payback to the invaders.
Spare no-one!