I'm very happy to see Obama up in the polls, but I'm also a bit paranoid about the voter suppression antics the republicans are up to. This post on TPM is very eye opening. RFK Jr. has written very comprehensively on the topic. There is this article from 2006 and now he has a website with Greg Palast dedicated to Stealing Your Vote Back. You can also see his thoughts on the 2008 election here.
On the other hand it's incredible that Obama and his Campaign are calling this out: "They are going to try to raise questions. You know, cry out and raise questions about fraud and try and create a smokescreen out there to confuse voters and perhaps to give cover to some of the activities they're going to be undertaking over the next three weeks." They have clearly learned from the weak handed performance of the Kerry campaign. We'll have to see what happens.