Wal-Mart's unilateral decision to put its purchasing and communication power behind going green also shows that a single company using its unique clout can accelerate public action to reduce greenhouse gases and reverse climate change. By rolling out an environmental labelling program disclosing to consumers the environmental costs of making products sold at Wal-Mart, the $401 billion retail behemoth has transformed green standards from nice-to-have to must-have.

Say au revoir, adios, auf Weidersehen, zai jian, and rest-in-peace to environmental skeptics and laggards; they are soon to be out of the picture. And it did not take legislation to neutralize them. It took a principled action by a self-interested company. That is values-based capitalism at its best.

This is one small step for Wal-Mart and one giant leap for Planet Earth. It is also one enormous demand on suppliers, among them many small companies that will feel crushed by the giant's new non-carbon footprint. But though Wal-Mart spent $200 billion buying from 56,000 U.S. suppliers in 2007, a high proportion of Wal-Mart's total annual purchases emanate from China where it's high time environmental standards are raised.

The beauty of the Wal-Mart innovation is that it doesn't ask anyone to change anything except the information that is provided and received. If polluters want to keep polluting, they are free to do so as long as they provide that data on their Wal-Mart labels. And if consumers choose to buy from polluters whose labels they can read, they are free to do so. In theory.

In practice, of course, we know that suppliers will change their practices to avoid embarrassing disclosures, and consumers will think twice about the choices they make. Consumer activists have been clamoring for information. At a recent conference discussing the company of the future, many seemingly informed people were astonished to learn how many gallons of water it took to make just one cup of Starbucks (or anyone's) take-out coffee - they had forgotten irrigation of coffee plants, fluids consumed by transportation of coffee and manufacturing of paper cups, and so forth.

We also know that the Wal-Mart concept is certain to be emulated by other retailers in their own ways. Who could possibly hold themselves up as Not-Green when over 130 million people visit a Wal-Mart store every week, according to company figures, and are made more conscious of environmental concerns? You can bet that a competition will ensue among retailers to out-do Wal-Mart in having the best green-oriented program. That might make "cheapest" the battle of the past and redefine "value" in the minds of consumers and the public.

Wal-Mart is not the first company to go green, nor even the first to reach deeply into its supply chain to require that suppliers meet particular standards. But it is the biggest, the most visible, and the least likely, given its past reputation. Its transformational action turns Wal-Mart into what I call a "SuperCorp" - a vanguard company that uses its power to improve an outcome for society, while knowing that its innovations will create profits as well as social benefits. In my new book, SuperCorp: How Vanguard Companies Create Innovation, Profits, Growth, and Social Good (to be published in August by Crown), I identify a number of companies ahead of the pack in innovating for the good of society and raising standards, often in collaboration with public officials, while still keeping an eye on the bottom line, including Procter & Gamble, IBM, Cemex, and Cisco.

Wal-Mart had been the company that the left loved to hate, because it seemed to have too much power and to use it in non socially constructive ways, squeezing suppliers or keeping wages down. Today Wal-Mart reminds us that a new kind of capitalism is possible in which big companies can use their power constructively, for the good of society and to move on issues that are still largely unaddressed by government. Clearly self-interest still prevails; Wal-Mart would not be taken the labelling action, with all of its complications, if its decision-makers did not see a definite commercial market benefit.