This isn't the only one, there are many NVC wikis.
The Nonviolent Communication book site: http://nonviolentcommunication.com/
The Center for NonViolent Communication: : http://www.CNVC.org
Emergence of NVC: A scalable, Power-With vision for learning, living, sharing, and evolving NVC Consciousness.
NVC Evolves. Explorations in evolving the understanding, living, and teaching of Nonviolent Communication. An open blogspace.
NVC Academy learn NVC online.
Web pages tagged "nvc" at del.icio.us: http://del.icio.us/tag/nvc