FreeCulture.org (Students for Free Culture) has just published a thorough and detailed post calling for the retirement of the non-free clauses, NoDerivatives (ND) and NonCommercial (NC). They state, "The NC and ND clauses not only depend on, but also feed misguided notions about their purpose and function." and that "Instead of wasting effort maintaining and explaining a wider set of conflicting licenses, Creative Commons as an organization should focus on providing better and more consistent support for the licenses that really make sense."