Bloggers can be kind as well as cutting when talking about national retailers and brands. In fact, they have more in common with mainstream media than many marketers suppose.
Full article by eMarketer: http://www.emarketer.com/Article.aspx?R=1007054
This article's focus on blogs is interesting, but too narrow for me to say - phew!
As a product manager/product marketer, my interest in what's being said online includes review sites (Yelp, Amazon) and social networks (Facebook, Twitter). These channels have a broad reach and a few loud negative people can make a lot more noise than their numbers suggest. I think Facebook is an interesting case study. When they launch a redesign, there are always loud unhappy noises. And then a Facebook group will form around the topic. From the # of group members, it becomes clear if the loud voices are representative of the majority, or not. Thanks to the social networking activity, Facebook product management can look at these indicators to decide whether to react, or to wait and let members get used to the changes enough to see the benefits.