to buy local or not to buy local

I've been hearing more and more about 'buy local' and 'food miles' (or 'food kilometers'). At first I thought this preoccupation with the distance covered by the transported food, from farms to supermarket shelves, made a lot of sense.
Recently however, I read "Food miles. Green good sense, ill-considered hype, or naked protectionism?", by Ethan Zuckerman, in worldchanging, and learned that the environmental impact of the food we eat should not be measured only by the distance it travels.
And in case you're a New York Times Select subscriber, you can also read "Don't buy local", by Richard Conniff, for another balanced view on the subject.
This debate is far from over and will certainly shape the way we buy our food from now on.
PS: I have truly enjoyed reading Richard Conniff's blog in the New York Times (unfortunately for subscribers only, sorry). Apart from learning a couple of German words - schadenfreude (pleasure taken from someone else's misfortune) and gluckschmerz (luck-pain, or sorrow at someone else's luck or happiness) - his writings offered an insightful look at human nature that were a delight to read.