The feared greenskin Orks faction is detailed in this multiplayer video from THQ. (Still trying to place that accent... Austrailian/Road Warrior-ish?) Be sure to also check out the publicly available multiplayer beta via STEAM and Games for Windows Live Marketplace which includes 5 maps and 4 playable races.
The beta will tide you over until the game hits stores February 19 for the PC.
Warhammer 40,000: Dawn of War II Orks Faction