It's a 'classical' Italian method - 'pollo a la mattone'. Usually you marinate the chicken in a lemon/garlic/maybe rosemary, maybe oregano / olive oil marinade, then cooking the chicken under the brick (either stovetop or grill) is supposed to make the skin extra-cripsy and yummy, and the meat tender, as it cooks more quickly. I've been wanting to try it, just haven't gotten around to it. If you google 'chicken under a brick' you'll get lots of recipes.
Michael Chiarello did this on one of his shows in the past couple of days. His method was a little ala Alton Brown. He said that on the day he wanted to make this dish he didn't have any bricks handy so he looked around to see what else he could use to improvise ... he took a large clay flower pot, pulled the plant out, wrapped the bottom and up the sides in foil and set it on the chicken!