Recruiting.com has a great post on how Corporate Blogging is a conversation, and not just a PR activitiy to create ‘spin’.
They list a great summary of the types of blogs companies should look at:-
Companies. You need a blog. Not a corporate blog, and not one.
You need: Passionate employee blogs.
You need: Job Blogs
You need: A job applicant process blog
You need: A vendor blog
You need: CEO Blog