I don't really have an opinion as to whether or not ACORN is guilty of registration fraud, but given the hysteria on the Right over this issue it's worth pointing out that registration fraud and voter fraud are to distinct things. What people refer to as registration fraud can be as simple as filling out a form incorrectly. It's certainly true that you can fill out a form for a potted plant or your dog.
What is far more difficult and rare is actually getting a registration card for your plant or your dog and then showing up to vote more than once on election day. Fortunately registration fraud is far more common than voter fraud, since the latter is practically non-existent, and without it, the former is basically meaningless. A far greater threat to fair elections are the kind of voter intimidation and caging schemes that we've seen applied in past elections, and that some organizations are aggressively fighting this time around.
This is exactly right. Despite all of the braying by the right-wing this raid yesterday is not indicative of massive "voter fraud." The right is desperate to find voter fraud and they have essentially no evidence of isolated voter fraud much less systemic voer fraud. Yesterday's ACORN raid does nothing to change that.