Exit polling and Early Voting

I was reading a blurb on Slashdot tonight about early voting problems in Florida, where a guy supposedly pushed the button for Jim Davis three times(first time was by himself and I guess he had a poll worker help him the other two times) before it regestered a vote for his candidate of choice. After reading this, something in my brain clicked when I saw "early voting problems" and I began to think about exit polling. "just how do they do exit polling in early elections?" I thought.

Supposedly Exit polling is a good measure of how people are actually voting. And, if, for instance, the results don't match the actual tally of votes, then one can assume that something's not right. But, with early elections - where the voting is stretched out over a period of time - how does that effect exit polling, and our ability to make sure elections are fair in a era of hackable electronic voting machines?

Exit poll data - asking voters which way they voted as they leave the polls - are used around the world as excellent predictors of actual vote counts, usually accurate within a fraction of a point. Exit polls in this election seemed to match the vote tallies, as usual, except in those areas using touchscreen voting machines (like the Diebold Accuvote) or other software or modem-mediated electronic systems (like those from ES&S) with no paper trail - used by approximately one third of voters, many in swing states. 80% of all US voters [emphasis in original article] use some kind of voting machine from one of these two companies.

-From Wikipedia in reference to the last presidential election in 2004

Vercellotti says standing outside polls and sampling those who vote
early would be labor intensive and costly.
"You'd have to have someone outside the polls every day for two
straight weeks or more,'' he says.

A better way, he says, would be to telephone a sampling of people who
have already voted. A list of early voters is considered public and is
available from the county election board offices.

Leaders of the Guilford Democratic and Republican parties say they
aren't polling early voters. It's not in their budgets. County Democratic
Chairman Tom Coley says his organization's only interest is motivating
Democrats who haven't voted to go do so.

-From "Early voting may add twist to exit polling". See link below.

I have no answers, only questions. Anyone?


Other links to related stories:

Officials Wary of Electronic Voting Machines - NYTIMES

Early voting may add twist to exit polling