I knew some cool Freegans back in my neo-hippy days. I'm all for the principles of Freeganism, but I'm not holding my breath that it'll ever be anything but a fringe movement.
I mean, come on -- you're asking people to take food out of the trash. There's a LOT of cultural hang-ups to get around there, way more than asking people to switch their light bulbs or drive slower on the highway.
The New York Post followed a few Freegans out for a nights "shopping", check it out.