Oh geez ... Tim Cavanaugh doesn't like blogs. I think. It's kind of hard to say. I didn't really find his point till about 3/4 of the way through his article about war blogs. He had to list about a gazillion links first (each with an appropriately witty remark preceding it).
Blah blah blah ... I guess he had a word limit to make. But when he actually gets to where he's going, it's a legitimate observation - bloggers don't have an, "...our man in Afghanistan." To a large extent, they require the mainstream media for information. But if he actually read some of the blogs, he'd see this is not the point. The purpose is comment and critique on the information available, and how the information is presented. I don't think anyone is pretending to report the news - just reflect on it.
His column also illustrates the biggest weakness of many (if not most) blogs, although he doesn't pick up on it. It's the same weakness traditional media has with its commentary, discussions and so on. It's the absence of genuine debate (or dialogue, if you prefer). While points made are often good, they tend to be buried beneath mounds of name-calling and elaborate efforts to be witty. Umm ... kind of like Cavanaugh's blast at war blogs. Will any of these people (say, Andrew Sullivan?) ever change Noam Chomsky's opinions? No. Will he ever change any of their's? No. This is largely because they never talk to each other, and their heels are so dug in when it comes to a position. Each talks to him or herself, and to those who already agree with their opinions.
This "preaching to the choir" is not the province of blogs. It's the characteristic of human beings in an age where everyone talks and no one listens.