[UPDATE 24-Nov-2006: Google has added an aerial photo of the site to the built-in imagery so you can see the logo was really there. Here is the actual location

Learn more about how they made the Firefox Crop Circle here. More on the making of the Firefox Crop Circle (including a video).
About Frank Taylor
Frank Taylor started the Google Earth Blog in July, 2005 shortly after Google Earth was first released. He has worked with 3D computer graphics and VR for many years and was very impressed with this exciting product. Frank completed a 5.5 year circumnavigation of the earth by sailboat in June 2015 which you can read about at Tahina Expedition, and is a licensed pilot, backpacker, diver, and photographer.