Last month the U.S. Government Accountability Office (GAO) came out with a 100-page report titled "INVASIVE SPECIES - Cooperation and Coordination Are Important for Effective Management of Invasive Weeds" (.pdf). In it, you'll find a survey of stakeholders, state-level case studies, and obvious statements like "lack of consistent and adequate funding limits effective weed management." Most interesting, at least to me, is Appendix II, which includes a comparison of each state's definition of what a "noxious weed" is. While the boundary between "noxious" and "invasive" continues to blur, only 5 of the 26 states with statutes defining noxious weeds specifically consider environmental harm when designating a species.
Thanks to a member of the ALIENS-L listserver for posting a link to the report.