Most of the discussion about e-voting centers on trust and the fact that evoting systems are generally a lot easier to abuse than to audit - but here's something from Robert Novak's political gossip column showing that bad interface design can unintentionally affect an election outcome:
Selection of a consensus candidate with a long, complicated name menaces Republican efforts to hold former Rep. Tom DeLay's Houston-area congressional seat. A write-in was forced by a federal court ruling that the GOP was too late after DeLay's resignation in putting a new name on the ballot to face the Democratic candidate, former Rep. Nick Lampson.
The vast majority of voters in the district for the first time will use eSlate voting machines that will require voters, for a write-in, to dial up one letter at a time and press "enter" after each letter. It will take around two minutes for a voter to dial in the name of the Republican candidate, Houston City Councilwoman Shelley Sekula-Gibbs (with no option for a hyphen).
Sekula-Gibbs's name will be on the same ballot for a separate election to replace DeLay for the last two months of his term. Republicans pressed for this special election in hopes it would help voters to write in her name for the full term.
What do you want to bet that they have to spell the name right for the vote to count? And, more to the point, how do you think the media and the Democratic party would be reacting if this affected a democratic candidate in, say, Broward County, Florida or King County, Washington?