I believe that there is significance in the way in which Hester Prynne is said to be at "about the height of a man's shoulders above the street." There is a sense in which Hester Prynne, being made to stand on the scaffold so high above the crowd, is shown to be morally superior and "above" the kind of narrow-minded thinking that has only been able to punish her because of her pregnancy. If we bear in mind the kind of criticism that this novel contains regarding Puritanism and their strict adherence to a creed of laws that make them seem more Pharisaical than Christian, the way in which Hester stands with such dignity on the scaffold only serves to reinforce the central idea of her godness and purity. Note how Hawthorne describes her:
Had there been a Papist among the crowd of Puritans, he might have seen in this beautiful woman, so picturesque in her attire and mien, and with the infant at her bosom, an object to remind him of the image of Divine maternity, which so many illustrious painteres have vied with one another to represent...
This quote of course is highly ironic, and it is an irony that is not lost on the author, because obviously the image of purity and sinless motherhood that Hester could be said to resemble is the opposite for her reasons for being there. Nonetheless, I think it is clear that the way that Hester is raised up from the crowd shows her different way of thinking about her "terrible sin" and how she is able to look upon it in a maturer and more understanding frame of mind, in spite of the hostility and punishment that she faces.