I started becoming interested in eating food that is grown relatively local the last time I heard about tainted apple juice from China. It was really shocking to me that the USA would import apple juice of all things from China.
We actually do pretty well in terms of eating locally. We buy half of a cow from a local farmer about twice a year. My father in law is retired and spends most of his spring/summer free time gardening. His garden is a poster child for miracle grow, and we are able to can a lot of tomatoes, peppers, beans, etc. Even though we do pretty well in terms of eating locally I think we could do better, especially in terms of breads, fruits and dairy products.
I was googling around and found some interesting links regarding eating locally. NPR had a piece on this in August 2006. LocalHarvest is a website to help locate farmers and farmers markets. These guys developed a 100 mile diet in Vancouver. They ate food grown within 100 miles of them for a year, and wrote a book about it. NPR covered it here.