According to this article Apple’s new OS has the potential of saving $10M in energy annually.

Windows 7 has been boasting how it'll consume less energy and save users on battery life and energy costs. But Apple won't be left out on this angle for their OS. According to a CNET review, Snow Leopard could help users cut back on energy consumption by around 10%, and that means an overall savings of as much as $10 million could be realized.