The Colossus has made its way onto the Starcraft 2 webpage.

"The towering colossus is a protoss robot design dating back to the bloody conflicts of the Kalath Intercession. It strides across the battlefield on four tall, slender legs which give it an extremely high level of mobility. The great height of the machine allows it to step up and down cliffs and other steep elevations with little difficulty, and gives it a dominating field of fire."