Last night, I watched Hacking Democracy. This movie documents, in several ways, how Diebold voting machines can be "hacked" in order to change the results of an election.
I think the US government should require a open and transparent audit of all electronic voting machines. Ideally, the software running on these machines would be required to be open source, so there would be complete transperancy to the code, but that is unlikely to happen
The documentary is available on Google Video