A update on the Dawn of War II community site reveals that the Tyranid race will be making an appearance in Relic's upcoming RTS sequel Dawn of War II, a single screenshot is also included in the post.

"Each Tyranid is a living weapon, perfectly adapted to its designated function, but each creature is no more than a single cell in a galactic entity governed by a monstrous Hive Mind. As the Tyranid hive fleets drift through space they strip all life from the worlds in their path, leaving nothing but scoured rock in their wake…

…In the war zones of Warhammer 40,000, the Tyranids are instinctive masters of swarm-tactics and close combat. Frequently appearing by the thousands across untold numbers of world, they always outnumber their opponents, a fact that often guarantees their victory. Each Tyranid is equipped with diamond-hard rending claws, razor-sharp teeth, and a variety of other bio-weapons suited to both close quarters fighting and ranged attacks. What’s even more fearsome are the monstrous creatures striding through a Tyranid swarm like Carnifexes and Hive Tyrants, true behemoths who tower over even the largest of tanks and mechanised units. In total, the Tyranids are a cold and brutal opponent to face. Even the best warriors in the galaxy can only hope to stall the Tyranids’ advance."

They sound quite unpleasant.