Cities can give property owners a property tax credit for growing food whether in ground or in containers. A greater tax credit can be given for those who generate income through their efforts. They may have to change zoning to allow for market gardens on residential property. A municipal composting facility can recycle organic waste and sell it at cost to the urban growers.
Cities can create jobs by paying urban farmers who live in the city to raise food on school property. The funds being spent to purchase food from vendors can pay the farmers' salaries. This could be done at any municipal facility that has land or other space for container gardens and purchases food.
Heck, I've got a whole program I'm working on formalizing for Atlanta that a city could implement and spur the local economy while localizing it's food. I'd be happy to talk to you about it. Perhaps you could present it to your city council if you like it.
There was a book I came across at the library > 10 years ago published back in the late 70's/early 80's that I think was called "Edible City" based around a coalition in Eugene, OR. It looks like there is a book with that title now on Amazon regarding a project in Toronto, so I may be off a bit on the name.
It was a very "homemade" feeling book, but it had a lot of insights in to how a city could truly be made in to a productive and healthy environment.
This site has a mention of the Edible City Resource Center, which if I recall was a sponsored site where people could come for free and learn about composting, vermiculture, growing veg/fruit/nuts and get classes in food storage, like canning. http://www.lanefood.org/about-wffc.php