Cringely’s promised conclusion is here; he notes that
If you could prove with an official receipt that you voted for Mr. Big, then it would be practical for Mr. Big to buy your vote, becoming Mayor Big …. My favorite voter receipt idea is the Vreceipt, which creates an auditable receipt that can’t be read by the voter or by Mr. Big.
— and ends up suggesting, whaddaya know, pencil and paper ballots, counted by hand.
UPDATE: InfoWorld has the latest (~1,000 words; reading time 5 minutes).
Actually paper ballots with optical scanners are available, cheap and in use. In Florida in 2000 the scanner counties had error rates that were about 1/10 of those in the punchcard counties.
The real problem is the american federal system which requires 3 levels of voting at a minimum. Also most state and local ballots are clutered with meaningless offices (Why aren’t the Coroner and County Engineer civil service offices?).