The Marvel booth at San Diego Comic-Con is always filled with little hints about and peaks of the Marvel movies, especially in the form of props. This year they had Ant-Man's helmet, Captain America's shattered shield, Loki's scepter and, unannounced, the body of Ultron Mk 1.
This is the versionn of Ultron that first attacks the Avengers in the party scene shown in Hall H yesterday. You can get a sense how the robot is made up of all different pieces of metal, including an Iron Man helmet. Over the course of the film Ultron grows and evolves, so this is just his first form.