re: Criticism of PR out of line
Jim's right: "encourage them to participate and write their own blogs" is definitely a more helpful and consistent position with regard to PR people and blogs.
The problem is, PR wants it all. They don't want to blog along with all the other employees, they want to control your company's one corporate blog. Look at the GM Fastlane blog for example, it's run by a team of Marketing/PR people and a couple of outside blog consultants. Sure, the GM execs do some of the writing, but it's certainly not a blog in the blogs-as-authentic voice sense; it's an always on-message corporate newletter.
So, I have to agree with the Debbie Weil quote "don't let your PR department write your blogs" (in Does your company belong in the blogosphere?). Instead, encourage your employees blog freely and set them up with infrastructure to help them do that.