As an ex-journalist and a blogger -- granted, one from Canada -- I can tell you that you'll probably be safe from accusations of copyright theft if you do both of the following:
1) provide a difect HTML link to the story.
2) only copy and paste the *most* relevant parts of the story up for discussion or, maybe, the first three or so paragraphs.
Most of the time, people in the media business are too busy to go after Web sites and blogs for this sort of thing -- unless you're somehow making a profit from using their news stories, of course, or maybe offering something that's only meant to be available to subscribers only.
If a paper is offering the story to the Web for free, even for a limited time, they already know that it'll be passed around and shared. In fact, they pretty much *expect* it and derive a lot of prestige from it these days.