Below are some links to sites that have info on roles various cities play in promoting urban agriculture. Most focus on community gardening. In general, the way that municipalities are offering this support is in providing land, water, other infrastructure, organic matter (compost, back fill with plantable soil) and other support (clearing land, bulldozing up asphalt, etc.). Often (and the Seattle example is a good one) the management of these spaces is contracted out to a non-profit that deals with day-to-day operations. I don't know about funding in these circumstances (contracting to a non-profit), but I suspect the City provides some or all of operating funds, with additional funds raised by the non-profit staffs. In some cases, management of these spaces is run through the parks and rec departments and additional manpower is provided by volunteers.
Generally speaking, most of the city-run spaces are on a community-gardening model which is usually people growing for household consumption. This does not address the prospect of people farming within a city as their main income. For that, try looking at this page from the City of Albuquerque. Albuquerque and Bernalillo County Open Space own a number of historic farmlands within the metro area. These parcels are farmed by independent growers for profit at a reduced rental rate. The idea is that they want this traditionally agricultural land to continue to be farmed so that it is productive. It also reduces the maintenance burden for those municipalities. Often they are run as demonstration farms and the public can visit and watch operations and special farm-related events may be programmed there. This link shows a couple of examples:
http://www.cabq.gov/openspace/farmlands.html
So, that's another possible avenue for support - the city renting larger parcels to small-scale, for profit growers at a reduced rate (to provide incentive)
Lastly, there is the issue of municipalities providing crucial information to growers (both household growers and for-profit farmers). Programs that help link growers with lucrative markets, run (or at least provide space and partial funding for) growers markets, profile successful urban farms, etc. are ways municipalities can and are providing support for urban agriculture. An example I linked to in my previous post (
http://www.mrcog-nm.gov/content/view/17/55/) is from a regional planning authority in the Albuquerque area. They have monthly forums on linking growers with buyers (restaurants, local produce markets, growers markets, Community Supported Agriculture, etc.) and a host of other topics. They profile successful farmers and their models as well as the buying patterns of restaurants and others, providing practical information on how to make this enterprise viable.
Ok, here are links to some cities that have programs in support of Community Gardening or Urban Agriculture in general. Again, support is mainly in providing land and water and to a lesser extent, management (or, money for a non-profit group to manage).
Portland, Oregon:
http://www.portlandonline.com/parks/...=39846&a=93176
Beaverton, Oregon:
http://www.beavertonoregon.gov/departments/gardens/
San Francisco:
http://www.parks.sfgov.org/site/recp...x.asp?id=27048
Article about what Mexico City is doing:
http://www.csmonitor.com/2008/0905/p07s05-woam.html
Denton, Texas:
http://www.cityofdenton.com/pages/pa...nitygarden.cfm
Seattle:
http://www.seattle.gov/Neighborhoods/ppatch/
http://www.cityfarmer.info/mayor-lau...ondon-by-2012/
A New York Times Article that talks about what New York and some other cities are doing. "Local officials and nonprofit groups have been providing land, training and financial encouragement." It also mentions a number of city and non-profits programs/organizations in the article:
http://www.nytimes.com/2008/05/07/dining/07urban.html
That should get you started and I hope this helps. Good luck. I would be curious to see what comes of this...