One of my sites was recently moved after having a good position under the appropriate category in ODP. It was there for about 9 months and then poof! moved to a totally unrelated category. It just so happens that the editor of the category that I was in also has a competitive site and works for another competitor.
At least the spidering engines don't succumb to jealousy, envy, and other human prone feelings. So much for fairness and the spirit of competition.