From the Google Earth blog:

Environmental Groups Leveraging Google Earth

The San Francisco Chronicle published an article - called "GREEN Eyes in the Sky " about how Google Earth is leveling the playing field for environmentalists by providing a powerful visualization tool. First, GE provides them with a powerful way to look at high resolution satellite and aerial photography of pollution, waste, industrial growth, and encroachment to natural areas (see example here). Second, GE is also a powerful presentation tool allowing them to not only see the ground in close detail, but also allowing the presentation of pictures, data (for example, waste sites, oil wells, etc.), highlighting rivers and waterways, showing deforestation , and more.

The SF Chronicle story highlights some examples of environmentalists using Google Earth. For example, the Sierra Club have put together a GE presentation on the encroachment of the Arctic National Wildlife Refuge in Alaska (here is the web site). Once you download it, make sure you look through the many options in the arctic.kmz folder you will find in your Temporary Places folder to see photos, movies, oil well placemarks, and other information they have provided.

Another excellent GE presentation was put together in response to some proposed logging in the Santa Cruz mountains of California. A concerned citizen put together a model showing where the logging would be done and the effects on the watershed. This presentation resulted in the proposed logging plan was withdrawn.