Arianna got a huge response to her anti-SUV advertising proposal. There is now a fund set up to pay for such ads on TV.
Salon has an interview with the author of the book "High and Mighty" about SUVs, in which he explains that they're not only bad for the environment, they're not even safer than other vehicles.
Even the Car Talk guys are starting to speak out against them.
I dunno if that is exactly "speaking out" but it's a start, at least.