We went from 6 foot cubicle walls to 4 feet or so to have a more "open" environment.  I liked the privacy of the higher walls, but I am sure for the majority of people, it is better.  I work right across from my bosses office and have a conference room I pop in to make confidential calls.  I do think it is helpful to be near the bossie office, but there are times I wish I was way across the room!