Clearly the Republicans have decided that they're going to try to turn ACORN into a Willie Horton-type symbol for this campaign.
Not content to simply launch a coordinated campaign of voter suppression across the country, the Republicans have decided that they are going to use ACORN to accent their politics of racial fear.
By raising the spectre of a grassroots anti-poverty group with roots in minority communities (ACORN) somehow flooding the voter rolls with thousands of fake voter registrations (especially from communities of colour), the Republicans are attempting to spread fear that minority groups are trying to steal the election for Obama. This is nothing more than another one of their "guilt by association" tactics against the "community organiser" Obama.
As is becoming increasingly clear from the ugliness voiced by the crowds at Republican rallies, the McCain/Palin/RNC campaign have decided that the only way they can win is by feeding the basest instincts of voters who are frightened and angry. Turning that fear and anger onto Obama specifically and African-Americans in general is the basis of their campaign.