Mathias_eichinger released the first beta of his new mission pack, which for now only includes 3 missions, Proxy War on the Armaholic forums.

Quote mathias_eichinger :
This mission pack contains 3 missions using addons, connecting some units from Arma 1 to the Arma2 world and is meant to be played in singleplayer.

Witness the new enemy as a mercenary field medic (Mission 1: The Surprise), receive your baptism of fire as a sniper (Mission 2: The other side) and fight off the enemy as a mortar section leader in the CDF (Mission 3: Hold the Bridge)