That is the question to which Bill McKibben proposes this answer, "Hit the streets and tell the U.S. government to take action against global warming."
McKibben is organizing (and writing about) a day of mass protests to get the federal government to take action about global warming. It is scheduled for April 14 2007 - "A National Day of Climate Action."
You can participate, communicate and watch how an internet-enabled, de-centralized, national protest happens (or not). Click here to read his first post and here for information on Step It Up 2007.
So what for philanthropy? This effort exemplifies how community action is changing. McKibben - working through nonprofits, blogs, and online magazines (GRIST) can get the word out nationally, folks can organize locally, good ideas will flow in all directions, and who knows - a movement just might happen. Two foundation grants are paying the effort's organizers ($100/week) and for the website. Existing nonprofits are key partners in the effort. If you check out the FAQ on the StepItUp site you'll find some good answers to strategy questions.
Funders need to understand how this type of organizing works. Here's a way to learn.