The trackbar is in the same plane as the drag-link. It stiffens the suspension and keeps the axle at the correct distance for the drag-link. When the suspension compresses it will push the axle slightly off center which keeps the wheels inline with the steering wheel Otherwise, when the suspension compresses it will cause the tires to turn. (This is because the distance between the pitman arm end and the drag-link end changes when the suspension moves.) This happens mostly when you are hard on the brakes. Since you instinctively try to correct for the turn, when you let off the brakes, the Jeep will pull in the other direction, usually left. (Hit hard brakes, pulls right, left off quickly, pulls left.) How much really depends on several things, spring rate, drag-link to tie-rod angle, amount of lift, how fast your going and how quickly you're braking.
You'll also notice that without the front track bar, the steering won't feel as crisp. This is because the suspension is now allowed to move a bit and therefor there is more play. The steering wheel will probably be slightly slower to center as well.
