An academic paper by Elizabeth Anne Roodhouse titled The voice from the base(ment): Stridency, referential structure, and partisan conformity in the political blogosphere analyzes six top political blogs and their coverage of Sarah Palin's candidacy for Vice President in 2008.
An interesting finding is:
Nonetheless, the relationship between stridency and partisan conformity exposed by this paper illustrates a trend amongst conservative blogs to repeat the allegations of “liberal media bias” often voiced by traditional conservative media outlets, contributing to an “echo chamber” effect in the blogosphere.
Furthermore, in the conclusions, we read:
The findings of this content analysis were simultaneously encouraging and discouraging. On the one hand, the relatively even–handed tone with which liberal blogs treated a controversial political opponent such as Sarah Palin was promising: while bloggers such as Arianna Huffington and Markos Moulitsas — the namesakes of Huffington Post and Daily Kos, respectively — make little pretense of non–partisanship, the majority of posts on their eponymous blogs voiced objections to Palin by mounting arguments that were bolstered by secondary sources, rather than spouting unsubstantiated polemics.
Some blogs, like Huffington Post, have veered away from this trend by adopting a more traditional model of journalism — creating a strict bifurcation between the opinions of online “columnists” and the reporting of public affairs and events, employing an increasing number of traditionally credentialed journalists, and publishing content from news wire services such as Associated Press.
Perhaps the most disquieting implication of this content analysis is the negative general valence of conservative blogs that overwhelmed accounts of a popular candidate. Surely, such wide gaps in valence regarding the depiction of Sarah Palin demonstrate differences between liberal and conservative blogs along the lines of partisan identification. Yet it is the paradox of two conflicting trends — the trend towards negative general valence and the trend toward positive valence regarding Palin — in posts about Palin in conservative blogs that make a stronger case that “partisan conformity” exists in the blogosphere. It is not surprising, of course, that conservative blogs reacted positively to Sarah Palin, whereas liberal blogs did not. It is surprising, however, that conservative blogs trended towards a general valence that contradicted their simultaneous support of a party candidate in posts about that candidate.
Although accounts in the mainstream media alleged that Palin’s candidacy ignited a “remarkably instantaneous” wave of support from the “electrified” Republican base, this ebullient enthusiasm — or even a moderate burst of positive energy — was absent from accounts of Palin in conservative blogs (MacGillis, 2008). Rather, the opinions expressed by conservative blogs echoed the allegations of media bias  and vilifications of liberalism in traditional conservative media outlets (such as talk radio or the op–ed pages of the Wall Street Journal) examined by Jamieson and Cappella (2008). As the name of the most popular conservative blog, Newsbusters, indicates, conservative blogs remain obsessed with “liberal media bias” that activates a “universally applicable rebuttal strategy” amongst their readers. And although Jamieson and Cappella concede that the echo chamber increases ideological coherence and encourages engagement, this approach also “massages” audiences’ “distrust in mainstream sources even as they continue to consume them.” .