Derek Lowe, defending chemistry blogging against the usual charges (no fact-checking, no editorial oversight, yadda yadda yadda) is absolutely right:
There is indeed a lot of inaccurate nonsense on the internet. And everyone should read what they find online with a thought to who's written it, and why. But everyone should do the same with stuff that's printed on flattened sheets of dead trees, too, even if there are flattened-dead-tree-sheet editors and fact checkers. This is no place to list the stories that have been horribly messed up by even the most respectable of the old media. I'm thinking of a good list right now; any well-informed person should be able to. (If you can't, you're not as well-informed as you think you are). And there is indeed a lot of good science reporting in newspapers and magazines, although we can't ignore the fact that there's an awful lot of lazy and sloppy science reporting, too.
But there's a lot of inaccurate nonsense in the peer-reviewed literature, too. Without editors and reviewers there would surely be more, but too much junk gets through as it is. And if you want to see that stuff flagged, you'll do well to read the chemistry blogs.
Professional journalists -- even (especially?) sci-tech journalists -- don't have a monopoly on the wide dissemination of sci-tech information anymore. And we're all better off for it.