Jay Reding has commented on my theme and concepts of the right-wing echo chamber. I responded on his site, but I'll repeat what I said here. (with a little editing)
Needless to say, I don't believe that blogs in-and-of themselves create the "echo chamber" effect, although they're certainly a contributing factor. Far more important is the conservative input in other media, including talk radio, the Internet as a whole (although that's mostly libertarianism rather than conservatism), television commentators, and various other media.
I'm also not quite certain [Jay's claims of] "depth and honesty" on the part of blog writers, either. because while blogs can serve as "bullshit detectors" (as much as any medium can for any other medium), that is valid only to the extent that they can detect each other's bullshit, care to call each other on it, and even seperate facts from opinions in the first place. Remove any of these, and blogs can as easily serve as sources of disinformation as information or, more importantly, serve as sources of opinion masquerading as facts, or one-sided assertions of partisan opinion as fact. I've seen and linked to several examples of this, including the Jane Galt affair, that dubious "DDT is harmless" junkscience.com article which Glenn Reynolds accepted uncritically, my observation of MWOwatch, Max Sawicky's InstaDebunking (and my own small contribution to that), and the presence of certain "litmus tests" that are imposed by the right to seperate the "good liberals" from the "bad liberals". As I said on my own site: "A bunch of bloggers passing around the same Krugman article and making the same weak arguments against it is not a debate".
Adding to this, of course, is the tendency of bloggers to agree with each other out of a sense of community. A blog is different than a web forum or a traditional web page- it combines both the relative immediacy and transience of something like Usenet with the relative permanence and high profile of a professional website. Getting caught in a battle between two blogs can be harsh both for the participants and for the readers in a way that is unlikely on Usenet and pretty much unthinkable on a traditional webpage, but I run across examples of these back-and-forth battles all the time. Sometimes they're beneficial (like that Middle Eastern debate that I mentioned earlier) and sometimes they're, well, not. (Isntapundit probably still winces when he thinks about our exchange).
Is this a claim that left-wing blogs don't exist? Nope... look to the left, I've linked to a few. (I should and will link to more.. I've just been putting it off because there will be a ton of them). There is, however, no comparison to the tight interconnected community that the right takes for granted (as well as the readily-available partisan sources of information online), at least as of yet. (And when I say right, I don't simply mean conservatism, but libertarianism as well). More to the point, as I've said time and again, is that the ideas of the right drive the debate both because of numbers, demographics, and the simple fact that the left is far, far more divided and troubled than the right right now. This isn't merely an "internet thing", but it exists, and it's closer to Sunstein's vision than many are prepared to admit.
(Heck, look at Instapundit. Sunstein was talking about how people would only read sites and look at sources that they agreed with, and who does Glenn readily link and cite? Either right-wing bloggers, partisan "think-tanks" like TechCentralStation or the Cato Institute, right-wing writers such as the staff at NRO, and right-wing mainstream media sources like the Wall Street Journal opinion page. And this is the most popular link source in Blogdom. Sunstein was righter than he knew.)
Edit: upon reading some of Jay's page, I've got to wonder whether there's a little bit of "cheering for the home team" here as well. Jay's blog is well written, but he certainly wears his ideology on his sleeve, and I've noticed that what outside observers refer to as the "Echo Chamber" insiders think of simply as community... after all, it's their own opinions being reflected and reinforced! He also seems to subscribe to the notion of a "liberal media" that I have a lot of problems with and only avoid dismissing out of hand because of my respect for the other, intelligent opinions of those who believe that it actually exists. This doesn't affect the quality of his postings, but it's something to keep in mind. (And yes, I'm aware that I may be overemphasizing the hegemony that may exist. No analyst should accept his own analysis uncritically. That's part of the reason I've been looking for examples of both the phenomenon that I'm talking about and counter-examples... because even if we don't have parity yet, I do think we're slowly moving in that direction.)