Check out the web site for his newest initiative, known as "350" (for the 350 parts per million concentration of CO2 in the atmosphere that is deemed to be sustainable - current level is 387 ppm):
http://www.350.org/
The 90-second animation explaining global warming without narration is worth the visit.
Current efforts seem focused on raising awareness of global warming, through social activities ranging from traditional rallies to postcard mail-ins to craft competitions.
Skeptics may question if there is any "there" there, the movement seeming to be all awareness and no action, but the 350 message is spreading globally at an impressive pace. Definitely a space to keep watching, to see if this global network of enthusiasts turns into a force to reckon with.
