The Matt Cutts blog post again is referring to file paths. (There are no underscores possible with domains)
Yes, he did also refer to a domain, but what he referred to is more the spam nature of using too many dashes in a domain, not that dashes are preferred over non hyphenated domains.
The two subsequent links apply again to URL paths, not domains.
The following link describes someone having more success with a non hyphenated domain.
The WMW thread goes into the theory Google can't process all that information to distinguish words in domains...an argument I've heard way too much before and I find completely irrelevant if I see exact match domains rank with ease.
Mind you competing results include authority sites with overwhelming more backlinks.
Then another link that is relevant to URL paths.
I'm sorry Minstel, but we'll have to agree with the fact we disagree on each others conceptions on exact keyword domains and associated advantages.