Today's New York Times carries an article entitled Indiana Essays Being Graded by Computers on a state-wide aptitude test that employs automatic grading:

...student essays were simultaneously graded by a computer and trained readers during a two-year pilot program. Using artificial intelligence to mimic the grading process of human readers, the computer's automated scoring engine, known as e-rater, generated grades on a six-point scale that were virtually identical to those of the readers.

The article then goes on to cite doubt about the idea from various students and teachers:

Kathryn L. Allison, the English department chairwoman at North Central High School nearby, doubts that the computer can accurately assess the quality of grammatically correct and well-structured student essays that lack substance or are wrong on the facts. "Are kids going to be rewarded for having pedestrian-type answers?" she asked.

So the automated grading system, which has no way of evaluating the substance and quality of answers, produces grades that are virtually identical to the grades of human teachers.

Welcome to high school.