David Holmgren , along with co author Bill Mollison, started the Permaculture movement when they published 'Permaculture One' back in the late 1970's. Since then David, along with his partner Su Dennett, have gone on to develop the property 'Melliodora', a Permaculture garden and orchard set on a number of hectares at Hepburn Springs just outside of Daylesford, Victoria.

Although the scale of this operation does not directly relate to urban gardens what they are doing with their property definitely does. David and Su offer tours of their property for a fee. Details can be found on their website. Well worth checking out.

If you are not sure what Permaculture is Wikipedia describes it as "an approach to designing human settlements, in particular the development of perennial agricultural systems that mimic the structure and interrelationship found in natural ecologies."