We have covered supermarkets and the food-retailing business quite a lot lately. Whether it's Hannaford's brand-new LEED-Platinum facility in Maine, the $1 million saved by Food Lion through a green IT project, Stop & Shop's seafood sourcing policies, or any number of other stories, supermarkets are both a hot topic and a large target when you're looking at the greening of business.

And at the Food Marketing Institute's Food Industry Sustainability Summit, happening this week in San Francisco, we get a good look at why the grocery industry is in the limelight.

"We need to begin to think of retailers as leaders in sustainability; they help consumers live more sustainable lifestyles and build sustainable consumption into their lives," explained Michele Halsell, the managing director of the University of Arkansas' Applied Sustainability Center. "They are the link between the suppliers and the consumers, [and] taking that approach to your role in the world is the start of an important transformation."

Along with other industry leaders, Halsell spoke to the more than 300 assembled attendees at the Summit this morning about the challenges the food industry is facing that are on or just over the horizon.

And the timing couldn't be better, according to Minor Sinclair, the director of Oxfam's U.S. regional office.

"Frankly, I think food retailers have gotten a bit of a pass over the last few years, but i think that's catching up," Sinclair said. Offering as examples Nike "getting hammered and then finding religion" on supply chain sustainability issues and the Gap succeeding through a policy of responsible sourcing, Sinclair said the food industry is likely next, given as how global the food supply chain has become, as well as the growing awareness of its impacts on people and the planet.

Retailers, particularly large-scale retailers like supermarkets and grocery chains, sit at the forefront of the opportunities and challenges presented by this global green shift.

Just as Halsell urged food retailers to look at themselves as leaders in sustainability, Jonathan Kaplan, a senior policy specialist at the Natural Resources Defense Council explained that, whether they see themselves that way or not, their customers almost certainly do.

"You the retailers have bought all the environmental impacts [of the products you sell] at every step along the way," Kaplan said. "That's a responsbility, but also an opportunity: you can have the biggest bang for the buck and you're in the driver's seat."

Because retailers are the point where the public and the manufacturers meet, they are the "point of sale," Kaplan explained, and as a result they're able to tell the story of the impacts along the way.

One of the best ways to both improve those impacts and communicate them directly to shoppers is through packaging -- both for better and worse.

"A lot of organizations who are just coming to sustainability look at packaging as a key way to address sustainability and communicate that to their customers," said Katherine O'Dea, a senior fellow at GreenBlue's Sustainable Packaging Coalition. "[Packaging is] a very customer-facing piece of what you do; when people take a product home, it's usually in a package, and they usually have to figure out how to deal with that packaging when they get home."

To that end, the leading retailers in the sustainability space are highly transparent -- literally and figuratively -- about what's in their packaging: Light-weighting boxes and bottles (reducing the amount of packaging), redesigning materials, incorporating post-consumer or renewable materials into packaging, and educating shoppers about minimizing and reusing packaging are all tried and true tactics being put to use in the food industry.

And when retailers do it right, it's a "win-win-win," according to Halsell: the environment, local communities and most of all retailers themselves all benefit from green initiatives.

But as evidenced by the breadth and depth of the summit's agenda, addressing environmental and social issues is a huge and complex task; to that end, Kai Robertson, the director of business and industry issues in food and agriculture at the World Wildlife Fund, laid out four things companies can focus on:

1) In the box -- improving a company's direct operations;

2) With the products on shelves -- addressing supply chain impacts;

3) Influencing your shoppers and community -- supermarkets are the cornerstone of many communities, they can influence kids and shoppers to think about environmental issues; and

4) Public policy -- advocating for public policies that promote sustainability.