The "Prinzessinnengarten" in Berlin are also producing local fruit and vege in an urban environment. However, as it is not sure for how long the space can be used as a plantage, all the plants grow in containers easy to move.
"Prinzessinnengarten" is used as plantage, hang-out spot for the community and farmers market: The products are sold "ready to eat" or "plant DIY". Occasional events even bring in the people not interested in organic groceries. Everyone is encouraged to join in, share their ideas and get their hands dirty.
What I like best is the idea about using standardized, industrial boxes to grow the plants in. Like this the gardening becomes more flexible and independent from urban planning: whenever necessary, the plants are ready to move.