There are currently 3 parks (of different sizes) at Jay Peak. They are worth it to take a quick run through on the way down.
Although yes, everyone is right in saying that don't go to jay peak for the park, I always find myself cutting through the 360 park on the way down to Tram side, because it is right by the lift and you can hit it after a good chute run or a tree run.
If you are looking to take park laps for a day, don't go to jay because the park is super minimal. If you are looking for some of the SICKEST tree skiing on the east, then jay is ur way