While I would be the first to point out that such opinions are a minority (although a large one), even on the Left, it's worth noting that this stuff is being printed up as legitimate commentary in places like MSNBC or major international newspapers.

The nutcases who are the right-wing analog of this kind of thinking--like the ones who think all the Mexicans should be deported, that teaching evolution in schools should be illegal, or that all the blacks should be shipped back to Africa--somehow never seem to show up in such places. They're mostly confined to the internet and pamphlet-on-the-corner ghetto where they belong.

This difference in how these different crackpots are received by the media and others is why I think left-wing nuts are more dangerous right now than right-wing ones.