The Security Group at the University of California in Santa Barbara has released theEvaluating the Security of Electronic Voting Systems (Thanks, Max!)
video that shows the attacks carried out against the Sequoia voting system. I heard about the video when talking to some members of the group, but it was never made available to the public before. The video was shot as part of the Top-To-Bottom Review organized by the California Secretary of State. Even though the review was carried our in July 2007, the video has been posted only now, more than a year after (why?).
The video shows an attack where a virus-like software spreads across the voting system. The coolest part of the video is the one that shows how the "brainwashed" voting terminals can use different techniques to change the votes even when a paper audit trail is used. Pretty scary stuff. The video is proof that these types of attacks are indeed feasible and not just a conspiracy theory.
Also, the part that shows how the "tamperproof" seals can be completely bypassed is very funny (and disturbing at the same time).