There's a massive campaign in the conservative media to connect the Obama campaign to the ACORN vote registration scandals. There does not appear to be a significant connection - certainly no suggestion that the Obama campaign has done anything to encourage ACORN to cheat on their behalf. Here's my summary of the situation:
ACORN registration fraud is at the individual level, where workers are padding their registration piles with fake registrations to make more money.
No signs that the fake registrants would actually be voting in the election. FOX is very conspicuously failing to talk about this, though I'd guess somebody will find a small number of ACORN people who had plans to go and try to vote based on the fake registrations.
It is possible, but I think unlikely, that there is a conspiracy on the part of ACORN to conduct a large scale vote fraud campaign based on the fake registrations. The evidence does not support this at all. For example "Mickey Mouse" mass duplicated names, and pro football name registrants are going to get scrutinized at the polling places and likely rejected.
Far more significant in terms of affect are the voter suppression campaigns where secretaries of state are removing huge numbers of names from the registration rolls. Often this appears to be a legitimate attempt to clean ineligible voters from the rolls but in some cases such as Ohio 2004 it appeared to be a very calculated approach to change outcomes. This year Ohio's voting process is under the control of the Democrats and it appears they are working too hard in the opposite direction - effectively having too few checks on the registration process.
The system failed in 2000, and Democracy is still reeling from our inability to qualify voters and count votes properly. Partisans who are more interested in outcomes that the Democratic process should bow their heads in deep shame (warning: do not hold your breath on this).