I just read this post on Ted Dziuba's blog entitled "Corporate Blogs, It's the PageRank, Stupid!"
My first clue was that Ted does not have comments enabled - trackbacks either. Perhaps he doesn't understand that a blog - corporate or otherwise - is about conversation, relationships, and learning from your market.
Dell Computer is the counter-example that immediately comes to mind, folowed by many others. Remember "Dell Hell"? Dell's stock price had tumbled. Del's igniting laptop made the New York Times. Del's support reputation was mud.
Dell started their blog - accepting comments and all. And Dell listened to those comments.
Dell understood that. I understand that. Who says corporations can't have tribes? Who says that blogs are not effective tools for corporations to connect with their tribes?
If a consultant tells you that corporate blogs are only for Google Juice, fire that consultant.