Who Should Be Responsible for a Brand's Social Media Outreach?

As social media continues to be a larger and more important part of a company's marketing strategy, one thing that is a challenge for big brands is how to decide who is responsible for this stuff? Is it the PR department or agency's job to blog, reach out to other bloggers, manage the company's online reputation, participate in the dialogue, etc? Or is it someone else's job?

Please Take A Peck at this survey and let me know what you think.