What Is This Astronaut Installing In the ISS?S

My first thought was: "Washing machine". Fortunately, NASA Goddard has the correct answer:

With his feet secured on a restraint on the space station remote manipulator system's robotic arm or Canadarm2, NASA astronaut Mike Fossum (frame center) holds the Robotics Refueling Mission payload, which was the focus of one of the primary chores accomplished on a six and a half hour spacewalk on July 12. The failed pump module is with DEXTRE on left side of the photo. NASA astronauts Fossum and Ron Garan performed the six-hour, 31-minute spacewalk, which represents the final scheduled extravehicular activity during shuttle missions.

[Flickr]