The blogsphere was at its outset a far more conservative place. The prominent pundits were conservative or libertarian (like Glenn Reynolds, Eugene Volokh, Bill Quick, Asparagirl, Lileks, etc.). I am sure some of these bloggers would be surprised at being labeled "conservative" so I apologise in advance for any mischaracterization (and invite corrections). Still, it was common knowledge that the blogsphere was right-leaning, and the very fact of its rightward tilt was enough to galvanize many second-generation bloggers to try and redress the balance (like Demosthenes, Matthew Yglesias, and Hesiod).
While meta-analysis of blogging abounds (too exhausted to even try and link!), as a challenge to traditional media, I think this overlooks a subtle and related point. The conservative media infrastructure does not "challenge" (ie, seek to replace) the normal channels. It seeks to influence it, so that by repetition of talking points, omission of background and context, the traditional media amplifies the conservative message. Were the traditional media to vanish overnight, and the offices of the NYT to sink into the ground, the conservative media infrastructure would be severely weakened.
The purpose of a liberal media home, then, would be to act as a reference, where the omitted bits can be restored and the context fleshed out. It needs to be complementary to the traditional channels. Instead of trying to influence it as the conservative side does, it needs to stand on it's own. A liberal media home needs to present all the facts, not just some, and discuss and analyse the context in detail, not in passing. Unpleasant truths must be openly discussed. Sacred cows have to be abandoned, dissenting voices have to be encouraged.
The net effect is to treat consumers of the mediahome as intelligent people instead of ravening masses, as thinking and reasoning beings rather than a machine to be greased. A liberal mediahome must cater to the readers' intelligence, not pander to its emotions, and above all allow the consumer to make up their own mind.
The liberal blogsphere is steadily evolving towards this standard. While Glenn Reynolds is not a liberal, he has certainly done his part to encourage dissenting voices, by virtue of a single link at times. But more is needed, like the exhaustive comparative economic analyses of Dwight Meredith, who has systematically analyzed government economic data to look at economic growth, inflation, unemployment, total and non-defense federal spending, the national debt, and number of federal non-defense employees, during a 40 year period under both Republican and Democratic administrations. This is a fantastic start, though of course one could argue that economic performance is more affected by who has control of Congress rather than the executive branch (the latter presents the budget and nominates the regulators and chairmen, but the former actually approve the budgets and nominations). It would be great to see someone build upon Dwight's research and do a similar analysis by Congressional breakdown.
Likewise, Eschaton has been a consistent reference to flesh out stories and information that simply don't appear in the mainstream (and which conservative commentators wish would disappear entirely). For example, this section of the Barbara Waletsr interview with Al Gore, which was not broadcast and exists solely in transcript form on the web (for now). Excerpt:
WALTERS: I'm not sure that people realize that while you were in the residence of the Vice President there were crowds of people outside screaming at you. What was that all about?
AL GORE: Well, this was the Republican response to what was happening during that 36-day period, and they organized busloads of people that came and stood outside the house all day and all night screaming at the top of their lungs.
WALTERS: What, "Get out!"?
TIPPER GORE: Things like that, yes, and, and sometimes � things that we don't want to say on your program, and, some people saw that they were buses from "churches," but it was organized. The one thing that, that they did mainly was reach the bedrooms of our children, and Albert was still in school locally, and trying to study, so we rearranged, you know, they � kids moved to a different part of the house, and I was trying to think of a way that we could kind of laugh about this since obviously it was out of our control, there wasn't anything anybody could do so I got all the boom boxes in the house and � I remember sort of what the government did with Noriega � I thought we'd try that, and I aimed them at, toward, you know, where the crowd �
WALTERS: The crowd?
TIPPER GORE: � And I put nature sounds on and turned it all the way up. And at least the kids laughed.
note how in the lengthy comments thread on Atrios' post, conservatives such as "Laura" and "Chris" attempt to downplay the incident, and are rigorously refuted. Also note that Walters admits that "not many people know" but still presumably did not consider this segment necessary for broadcast. Atrios has the patience and the resources to go slogging for those tidbits of information that provide critical context to daily events.
Another example of the evolution towards a true media home is the rigour of the arguments. For example, this post by Ampersand, which exhaustively analyses the issue of "husband batterring". It is well-argued with logical organization of the main points and extensive references to back up her assertions. These are real footnotes, not invented ones that populate Ann Coulter's book. While one can certainly find points to disagree with, it's obvious that Ampersand's analysis is a well-reasoned one, not a knee-jerk ideological stand. And by phrasing the argument in such structured and documented terms, a framework for further debate is created that truly advances the discussion and serves a useful purpose. The hilarious satirical cartoons are icing on the cake.
And finally, a rational and measured response to distortions is a necessary function. For example, in regards to the crusade by Martha Burk to get women admitted to the Augusta National golf club, CalPundit has a chronological analysis of how the central issue (the restriction of women from the club may be legal, but immoral) became hijacked away into relative minutae and scare-mongering with terms like "radical feminist agenda". As Kevin concludes, "The real issue is simple: Why? Why do they feel that admitting women would ruin their club?". This kind of documentation of how the conservative infrastructure can manipulate the debate is a powerful reminder of the cost of unilaterally disarming on the battleground of ideas. (Kevin is hard on Glenn here, and while Glenn defends himself, he still misses the point in bold above. It would be great to see him address that rather than the red herring of "double standards").
Across the blogsphere, liberals are beginning to form the individual pillars of a media infrastructure. It will likely never be completed, but it is fast gaining critical mass. Already, meta-blogs devoted to aggregating content on liberal blogs are rising up, like Progressive Gold (I've proposed something similar myself, as has Nathan Newman).
I urge all liberals to start a blog. You don't need to have a hundreds of readers, or be featured on Glenn's blogroll, or be the number one search result on Google. You just have to get out there and express your opinion. The sum total of these ideas is what will give liberal ideas - broadly defined as "finding the right solutions to the problems still facing mankind - a chance to evolve far faster than they can in the stultified arena of the traditional media. Do it yourself, don't rely on Instapundit or Eschaton or even UNMEDIA - contribute to the debate of ideas, join teh ranks, and have your say.
You are entering the blogsphere, liberals. Welcome home.
UPDATE: Dwight points me to this rigorous analysis of government spending on Calpundit's site, which arose out of a discussion between him and Max. I'm starting to wish there was a unified repository of liberal blogger data analysis. All of which - Dwights, Cal's, Max's, - do not assert ideological points but rather simply refute the ideological attacks of conservatives. Proving something false does not necessarily mean the converse is true! Liberal economic analysis understands this, conservatives don't seem to. I do wish that a conservative economic blogger like Jane or Steve Verdon would take a look at these, however, those are two conservative bloggers whose opinions I respect and take seriously. If they could be persuaded to join the analysis, that would truly further the debate, productively.
 I invite readers to Google for "Tubesteak Messiah"
 It is vital to understand that this analysis is NOT to "prove" that "Democrats are better for the economy than Republicans" !!! It exists as a counter-argument to the false claim that Republicans are better for the economy than Democrats. The myth of GOP economic supremacy is so pervasive that the stock markets routinely surge in anticipation of GOP victories, which has a real and detrimental effect on on the economy itself, in a meta- kind of way. (Curiously, though, that wasn't the case for the 2002 midterms). Still, proving A is not better than B does NOT prove that B is therefore better than A. Correlation is not causation, regardless of whether that correlation is positive or negative.
 Hunger. The Environment. Injustice. Oppression.