Okay, this is a great site with a purpose. Cliff Bar has long been known as a great place to work with a decision years ago not to sell and keep quality of life under company control. This seems to have paid off handsomly and now they are working on getting quality of life for the rest of us through environmental activism. This 2 Mile Challenge seems like a good start at getting critical mass around what is typically a "complicated" issue that involved international relations, taxes, science and more.
One of the biggest issues the environmental movement seems to have had is marketing. Here Cliff Bar as simplified this with some facts and actions that are easily at hand. One being that 40% of urban travel is 2 miles or less. This sets a concrete number, puts someting easily attainable (2 miles, not switching to all uncooked foods) and puts up an interactive space with map, blog and so forth to connect all these "2 mile heroes".
Will this work? I don't know. I am sure there are other things to tie this campaign togther and other best practices out there. Let me know your thoughts.