I'm listening right now to a relatively new (this spring) podcast, "The Queens of Green".
Deborah Koons Garcia and Temra Costa interview leaders of change in food, farming and related issue arenas.
Sometimes they interview one another, as in the one I'm listening to now, where Temra talks about her book "Farmer Jane" - about how her undergraduate studies in international agriculture and women's studies came together.
Women (30 are included in the book) are leaders in the sustainable food movement, they say - not just as concerned mothers, but as farmers, chefs, and so on. Temra excerpts her book, and both hosts manage to get in personal details and opinions ranging over a variety of related topics.
The interests reflected in the weekly 26 minute interviews are both regional (north and central Califorinia - it helps to know where the intersection of Ashby and San Pablo is) and global.
Here's their web site: http://www.thequeensofgreen.com/
You can also download the podcasts through Itunes.