It's all bullshit, of course.
Take a look at this if you want the truth about ACORN -- who they are, what they do, what this "voter fraud" consists of.
McCain talks about an assault on the very fabric of democracy, but there's far more of that coming from the right, with its efforts to disenfranchise minorities, the young, first time voters, and the elderly than from anything that ACORN has done. It worked in 2000 (Florida) and in 2004 (Ohio). We have to make certain it does not happen this time.