There is nothing impossible about it. Its just that if you have to pay for the power and compute cycles its not worth it without ASICs. If you're stealing time/power on (many?) computers and contributing to a pool you'll make a very small fractions daily.

Just a few points I wanted to clear up here. I helped out at the local precinct during the California primaries a few months ago. I helped set up and break down all of the machines. So let's talk about the lack of paper trails shall we? The touch screen systems seem to be what every one is worried about so well start there. When they are set up the current memory is printed out. All the people at the precinct look over the print out and verify that all of the tallies are currently zero. Therefore, at the start of Election Day: No tampering can have been previously committed. When you actually vote on a machine the results are printed to make sure that the values have been stored correctly. This is your first paper record of how the votes went. When the day is done we print out a finally tally of the votes which is again signed by all of the people working the precinct. One copy is hung on the door of the poling place and another is sent with the machine. Two people are required to transport all of the ballots to the main office. Yes there are holes in the system. If all the people working a poling place conspire it would be easy to fix those particular results. It would even be relatively easy for the two people transporting the results to forge other people's signatures and provide totals. In either case you still have the print outs from each persons vote that the voter verified was correct. Therefore you still have a verifiable paper trail if someone disputes the votes. I don't know why it isn't made more public, or perhaps our precinct just had special voting machines, but that is my personal axperience with the electronic voting.