Michael Herron, responding to this blog post, writes:

I just read the reference on your blog to the John Lott piece.
He says:
“Indeed, it is probably through the discovery of new votes that Franken has his best shot of picking up new votes. Despite the press pushing a possible replay of election judges divining voters’ intentions by>looking at “hanging chads” to see if voters meant to punch a hole, that shouldn’t be an issue in Minnesota. The reason is simple: optical scan vote counting machines return ballots to voters if no vote is recorded for a contested race.”
Lott is wrong about MN’s use of optical scan. My information is from the MN SOS (contact person is Pat; phone number 651 xxx xxxx; date of call 11/10/2008; time approximately 3:12pm eastern voicemail).
I was told by Pat at the MN SOS that MN’s machines are programmed to kick out overvotes and blank ballots but that they are not programmed to kick out undervotes (except in the case of a blank ballot, which is a collection of undervotes).