Well, we've had a tech bubble, a housing bubble and now we're getting predicitons of a food bubble. Biofuel production and speculators are being blamed. Accuracy of the prediciton is unknown, as is the accuracy of the model it's based on. Time will tell for the first, and I'm sure we'll start seeing some stories on the second shortly.
In reality, who's to blame won't matter nearly as much as the effects on your wallet and your stomach should a bubble start. While I, like many folks, could stand to lose a few pounds, I'd rather not do it because I couldn't afford to eat.
I wouldn't panic just yet. However, keeping a full pantry is simply a smart precaution that insulates you not only from price swings and food availability issues, but from life events as common as unemployment. It wouldn't hurt to be sure you're fully stocked.