Who's running the Margaret A. Cargill Philanthropies and what makes them get up in the morning? That's an important question as the Minnesota-based foundation takes its place as one of the largest foundations in the U.S., with assets of over $6 billion and annual giving up to $300 million. Margaret Cargill was the grand-daugther of William W. Cargill, founder of the Cargill Co., one of the nation's largest privately held firms. She died in 2006, but not before specifying that her estate would be used to support work in seven different areas, including the arts, the environment, disaster relief, and children and families. How this broad mandate is interpreted, exactly, will make a huge difference for nonprofits across the United States -- and so the vision of Cargill's leaders should be of acute interest.