It’s about how much testing should be automated and how much should be manual (programmer/QA/beta)
That’s what I think too. A certain amount of automated testing is clearly a good thing (eg Ayende’s example), but it’s always best to err on the side of real world, real user beta testing whenever possible.
If you have plenty of time time to code in unit tests and perform an extensive beta test period, then by all means do both!
Otherwise favor the beta testing heavily.