NZ Museums is a good example of the web 2.0 elements of diffusion and concentration (as I understand them!)
Diffusion in the sense of "richer connectivity between people, applications and data" manifests itself on the NZ Museums website in several ways e.g. the use of tags and tagging that users can attribute to objects in the collection may allow for a richer description and more access points to the material. Also, providing the ability for users to add comments on materials in the collection may add to a richer information experience.
Concentration in the sense that the site enourages collaboration among NZ museums and is an effort to pull collections together. But why no RSS!