Forecasters don't expect Hurricane Irene to make landfall until Saturday. But for nearly a week now, big-box retailers like Walmart and Home Depot have been getting ready. They've deployed hundreds of trucks carrying everything from plywood to Pop-Tarts to stores in the storm's path. It's all possible because these retailers have turned hurricane preparation into a science — one that government emergency agencies have begun to embrace.At Home Depot's Hurricane Command Center in Atlanta, for example, about 100 associates have been trying to anticipate how Irene will affect its East Coast stores from the Carolinas to New York.At times like...