Update: We have added a page to our Wiki that serves as a running list of PR firms that blog.  If you aren't listed, please feel free to edit the Wiki and add yourself.  Original post follows.

Around six months ago I wrote two posts (1, 2) about whether the world's largest PR firms had official, company sanctioned blogs.  I decided to loop back on this research to see if any companies had started blogging in the interim.  This time I also looked at the Technorati rank of each the blogs.   For the uninitiated, Technorati calculates the popularity of a blog by analyzing the number of incoming links a blog attracts. Although not perfect, this is a pretty good way to access the popularity of a blog.  Lower ranks are better.

In doing the research this time I was looking specifically for blogs that were linked to from the main website of the PR firm.  I know that individuals within all these companies are blogging.  The point was to find blogs that are supported and sanctioned by the PR firms.

Enough throat clearing, here is a chart showing the results, sorted by Technorati rank. If the company has a blog that I could find I have linked to it.

*Edelman links to a variety of blogs from their site. The rank listed here is for Richard Edelman's blog, which is listed first and the most represenative.  Obviously I know Micropersuasion is a Top 100 blog.

Some quick observations on these findings:

(1) 50% (9/18) of the companies had blogs that are linked from their main website. 

(2) 80% (8/10) of the companies that had blogs had updated them in the last week.

(3) Ogilvy has launched an official company blog in the last six months.

(4) Since my last article, it appears many of the companies have added links to their blogs on their homepage and made a commitment to update them more often. 

(5) Regarding the Technorati rank of most of these blogs, they are pretty much what you would expect.  Right or wrong, most of these blogs are aimed at clients and prospects who don't live in the world of blogs or  blog themselves.  The content is largely introductory in nature.  It just isn't that interesting to the wider blogosphere and thus isn't going to attract the links needed to earn a high Technorati rank.

(6) Despite the fact that many of these companies have blogs, only a few appear to really be focused on them as an integral part of their website program and marketing efforts.  Hill & Knowlton and Edelman were the two that stood out and seem to really place a high value on corporate blogging.  Some of the other blogs felt like afterthoughts.

If I've missed something, let me know.  And please share any thoughts you might have in the comments.

Update 1:  I updated the H&K entry based on a comment left by Niall Cook.

Update 2:  A reader helped me figure out H&K's actual cumulative blog rank.