I came across this article today on locally grown foods.
To sum it up, it says that buying local food isn't saving as much energy as one would hope. Most food is shipped across the country on trucks. A single trailer can haul a lot and when you divide the energy used on a per item basis it's quite small. Now take a local farmer driving to a market with a single bushel of apples. When you work it out the energy used per food item is pretty high, but still lower than shipping it coast to coast.
The article recommends locally grown food which makes me happy. Ladybug and I have been trying to embrace this as much as possible. That being said, at the very least everyone should buy local eggs :)