Oh hey there, do you want to see a terrifying robot George Washington with a gatling gun? Of course you do. You'll be having clockwork nightmares for the next few days, so make sure you enjoy it!
This is the Motorized Patriot, one of several "heavy hitters" that'll be coming after players in BioShock Infinite. In the above video, Irrational Games explains a little bit about him. He's a patriotic clockwork terminator, and he's going to shoot your face off.
Unless you shoot his face off ... and see the creepy dead metal skull underneath.