I'm currently in the process of creating a photoshop concept piece for a little enemy i like to call the Hellbine Soldier. I'm not going to spoil anything about who or what these Hellbine Soldiers are or how they fit into the plot, but I'll be sure to continue working diligently on the conceptual piece and get it posted up on the HL2: Desolation page A.S.A.P.
*Edit*
Hellbine Soldier Picture is officially up! Check it out in the images section.