Just inside the Flynn Theater in Burlington, Vermont, Ben Cohen and Jerry Greenfield stand aside as twentysomethings stream by to find seats at a rare hometown concert by the rock band Phish--a treat the ice-cream magnates have sponsored to raise money to clean up nearby Lake Champlain. A girl recognizes Ben. "Could I, like, make a suggestion?" she asks. "It'd be really great if you could make a marshmallow for us vegetarians."
You have just entered the socially conscious zone, where certain ice-cream lovers expect Ben & Jerry's Homemade not only to clean up the lake but to rid marshmallows of...