tedster - 11:02 pm on May 18, 2011 (gmt 0)

I suspect that "opinion" is easier to spot algorithmically than, say, "depth" is, even in a limited universe that's been defined as "news", so I don't think the classification is a trivial task.

Absolutely. The spectrum from subjectivity (opinion) to objectivity (factual writing) is a classic, foundation level metric in sentiment analysis - and many months ago Google said they have "world class" sentiment analysis in play on Google News.