Audi implements a clean desk policy while Herman Miller is more tolerant. An excerpt from the Fortune article:
Some researchers, however, dispute the benefits of a spotless workplace. When Herman Miller (MLHR), an office furniture supplier, conducted an observational study of workplace organizational habits, they found that "filers" actually stored more useless information than their unkempt counterparts. The company identified a group of "work masters," or efficient employees, and reported that those staffers were more inclined towards piling than filing.
[My own objective study has found that the messy desk people are better looking, fun at parties, and kind to animals.]