GamingBolt notes some activity on the Steam Users' Forums highlighting what's a discovery said to be found in the Alien Swarm SDK that is being taken as a clue that Half-Life 2: Episode Three is actually in development, or at least is still being planned. The post links an image showing an object purportedly from the SDK called "info_node_hint" with several Ep3 references. Feel free to sprinkle this with salt, though Valve has made a recent habit of letting announcement hints slip in odd ways. Thanks Ant via Digg.