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.

In a story I posted a few days ago, I found that 4 of the 18 largest PR firms had official corporate blogs (Burson Marstellar, Edelman, Hill & Knowlton and The MWW Group). Constantin Basturea wrote in with some corrections/additions to my list. Here goes:

• The Horn Group has a blog that I flat out missed. My bad. That's 5 of 18.
• Manning Selvage and Lee doesn't have a blog, but Hass MS&L does. I'll leave it to you whether that should count.
• Ketchum's Personalized Media practice has a blog that they update fairly regularly. However, Ketchum doesn't even link to this blog from the Personalized Media practice area section of their coporate site, and its the last entry on the second page of Google, well behind the faux Ketchum Ideas blog. I'll let you decide whether to count it.

Here are some other non-official PR blogs Constantin pointed out:

• Tony Obregon from Cohn & Wolfe is blogging.
• There are at least two senior execs from Ogilvy who are blogging: John Bell and Rohit Bhargava.
• Robert J. Ricci from Weber Shandwick’s Web Relations Group is blogging and the Weber Shandwick technology PR team in New York is blogging.
• A group of people working at Porter Novelli Washington is blogging.
• John Brodeur (Chairman of Brodeur Worldwide) has a blog.

Constantin also recommends this as a good listing of PR blogs. Please feel free to post any additional blogs I may have missed.