EPEAT has been around for a while serving in the capacity of eco-labeling for industrial products. For example, if a government institution wants to purchase a series of low energy computers or the like, EPEAT would rate systems for them. They are now expanding their functionality to serve the consumer market.
As mentioned in a recent Core77 post, their rating system consists of a gold, silver, and bronze ranking. Amazon is a major partner in implementing this rating system so expect it to get a lot of advertisement.
Keep the ratings in mind when you make your next purchase. If you can save the environment and some money in the process. It's a win-win.