This is simply the strength (torque) rating of the particular servo. Ratings are calculated using a one-inch long servo arm. Therefore, if you had a servo with a one-inch arm and it would (with input applied) hold a 200 oz weight, then you would have a 200 oz rated servo.
Dude, I think that the dual servos is the coolest mod I have seen. How is the steering response? Faster turning and smaller circumference? That is an awesome upgrade!!!!!