IBM Virtual World Guidelines (does your company have one?): "In general, your digital persona’s appearance is up to you. When you are using your avatar or persona in association with IBM, however, your judgment in these matters should be shaped by the same general guidelines that apply to IBMers in physical environments – i.e., that your appearance be appropriate to the context of your activities. You need to be especially sensitive to the appropriateness of your avatar or persona’s appearance when you are meeting with IBM clients or conducting IBM business."
-- via a comment on Second Thoughts
It was written up in USA Today last year, too.