When is plagiarism not plagiarism?

According to this story, a University of Missouri journalism professor resigned after he admitted that he plagiarized material from a student writer. It's a rather convoluted tale (you can access it by clicking on the headline), but apparently the only thing he "lifted" were quotes. Poynter author Roy Peter Clark seems to take the tack that it really wasn't plagiarism at all, but rather sloppy attribution.

Doesn't this beg the argument that a quote is a quote is a quote? Once the quote is out there, do we really have to say where it came from? I think we do, simply because such information is relevant to whatever we're reading. I do agree with Clark, however, that the "scarlet letter" of plagiarism can easily lead to witch hunts, inducing competent and learned journalists to quit the business at the first blush of scandal.

I'm not arguing in favor of Jayson Blair...but I think that genuine, time-tested and battle-scarred journalists are precisely the men and women we need in the field. It's probably safe to say that the UM professor won't make that mistake again. Would it be better for his students to leave him where he is, sadder but wiser? Or, on the other hand, is that endorsing the very behavior we expel students for?

I'm not drawing conclusions here. I just wanted to air both sides of the tale -- and let you draw your own conclusion.