A little over six months ago, Liquid Egg Product wrote a provocative post The demise of chess blogging I've been thinking about this topic lately...
The following is a revised version of the comment I left there at the time, with a new bit on the state of the chess improvement blogosphere and the Knights Errant in particular. Note this is focusing mostly on chess improvement blogs, not chess news blogs or blogs associated with a particular chess club.
Prehistoric chess blogs (?-2004)

Early on there were a bunch of disconnected blogs, most of them associated with local chess clubs or conveying chess news. People like Mig, Glenn Wilson, DG at BCC, were on the scene, but there wasn't a real community of independent chess improvement bloggers.
Growth Errant (2004-2005)
Then the Knights Errant emerged and basically ushered in a social network of interconnected chess improvement blogs. They focused almost exclusively on posting things like ‘Man, I did my tactical puzzles today, it was intense.’ Back then, Man de la Maza, Sancho Pawnza, Pale Morning Dun, and a few others were the gods of chess improvement blogging. DG, who maintained the BCC news-focused blog, kept tabs on the Knights Errant as part of his blogging. Indeed, the Knights Errant sometimes called him the 'Official Historian' of the Knights Errant.
For a while, almost all the improvement blogs were Knights Errant related. I was part of this growth spurt, as was Temposchlucker, J’adoube, and others. Plus, a couple of more eclectic blogs hit the scene such as the Kenilworthian and Polgar's blog.
Diversification (2005-2007)
Probably late 2005, we had an explosion of non Knight errant related improvement blogs, and the friction really started. Multiple threads of people saying the circles were stupid, many people modifying the circles (this started in early 2005), and lots of very healthy discussion of the best way to improve. The blogosphere became less incestuous. I think we can all agree this can only be good.
Perhaps the best examples of this genre are from Quandoman, Patrick (the dead Chess for Blood), Dutch Defense (blogs dead), and Loomis. These were solid players who tended to have strong opinions on what sucked and what didn’t (Loomis was an exception--he was always soft-spoken and just as often right). DK Transform also was part of this explosion.
In other words, the chess improvement blogosphere became healthy. Many people using different methods, or no methods, in their focus on the game of chess, came on the scene. The Knights Errant became one little cluster in a growing improvement world.
Explosion (2007-2009)
Then things simply exploded. Most of the improvement bloggers of those older times had disappeared, while a new breed of blogger in the form of Chessloser, Liquid Egg Product, Robert Pearson and lots of others began around 2007.
Just as the first wave of change was from circles-narcissism to general chess improvement, the next wave was another expansion of topics. Things became much more idiosyncratic, ungroomed, irreverant, and eclectic.
Centralize or demise? (2009-?)
It may be me, but it seems there is another shift afoot. It seems that chess.com has become a sort of center of mass of the chess improvement community online. They have a great interface for blogging and displaying games. Many traditional bloggers such as Blunderprone have started cross-posting their work on chess.com just to increase their exposure.
There are probably more chess blogs than ever right now, which means it is hard to get people to read your blog. It makes sense that people would go to chess.com, which has a built-in way to distribute your work to many people on their home page. You don't have to worry as much about getting people to link to you or read your work if you are on chess.com. They do that for you, essentially.
I frankly miss the days when it was pretty much only the Knights Errant, all struggling with the Circles. That may be one reason I joined the International Chess School (ICS) and started a forum so I could work through the class with a bunch of other people struggling. I like working with people on a common task. You build up camaraderie, familiarity, and a sense of collective purpose that is largely missing in the chess improvement blogosphere right now.
Not that the Knights Errant are completely dead. They still exist in name, but with few exceptions it is hard to find any discussion of the Circles or tactics on one of their sites. Certainly it is good that things are less monotonous, but there isn't much of a sense of collective effort coming from the Knights Errant anymore. With my little ICS forum, I've started to recreate that sense. It is fun working with a small community of people toward a common goal. Plus, it is more balanced than the Circles. :)
Take this with a grain of salt
At any rate, the above is my rambling historical dissertation on the chess improvement blogosphere. I'd be curious to hear your thoughts about what you think, where you might disagree. Please don't be offended if I left out your blog by name. I tried to pick representative examples of bloggers.
Note this is a cross listing of a post from my main chess blog.