In this HBO special, they brought in a computer security expert from Sweden or somewhere who hacked the memory cards, after he easily put a program on the memory card, they did a mock vote..
Here was the vote: Do you think that the Diebold system can be hacked? Yes or No
7 voted no and 2 voted yes. Then they ran it through like they would a normal election and when they hit the final tally button, the results came out 8 people for yes and 1 for no, all as a result of a very simple program put on the memory card..