Eight of the top 9 and 10 of the top 13 companies on the magazine's list of green companies are electronics and technology firms, starting with Dell at No. 1. Much of their accomplishments have been in the area of energy and greenhouse gas reductions, but companies like Dell, Intel, Sprint and Adobe all were praised for aggressive recycling and waste reduction achievements as well.

It's an impressively researched list but not without some probably unavoidable biases. It was generated from a list of only public firms, and the 500 largest. It's dominated by highly visible consumer companies, from IBM to Office Depot to Colgate-Palmolive to McDonald's. These types of companies have a stronger stake in having a green image than say a private B to B company. That's not to say that's why these companies are aggressively environmental, but it certainly doesn't hurt.

Also, many of the companies on don't generate the large and potentially more toxic products that can be more difficult to manage environmentally. Newsweek acknowledged the technology firms placed well on the list in part because they make often make lower-impact products such as software.

All the progress is great for the environment. But in a sense it shows that companies leading the way are sort of the low-hanging fruit. They are the companies who have to answer to stockholders and mass consumers, both of whom like quick gratification. But how much potential remains out there, with the private and public companies that make big products for business consumers, where the positive reinforcement may not be as blatant?