Many folks differentiate the role of social media from corporate blogging but it's important to note that blogging is simply a subset of social media.  Corporate blogging plays a superior role in a company's social media strategy because it builds a foundation for the company to both control their messaging as well as be non-intrusive.

Looking around at other mediums in the space - micro-blogging, wikis, social networks, email marketing, etc. a corporate message is viewed with a bit of skepticism.  Why else would a company be involved in social media unless they wished to manipulate us? Blogging is not met with the same skepticism.
  • Blogging builds compelling content that captures search engine traffic.
  • Blogging builds authority within the area of expertise you are engaged in.
  • Blogging builds authenticity and a personal relationship with your prospects and clients.
  • Blogging builds a knowledge base for clients to find the answers they are searching for.
There's quite a bit of technology behind a blogging application that most companies are unaware of.  The styling of text, the page layout, the submission process, the backlinking, the popularity, the competition, the recency, the frequency... all are components that are weighed and optimized for search engine dominance.

If your company wishes to dominate in its area of expertise, they need to partner with experts whose job it is to provide both blogging software and the service to assist you in dominating social media. Dominating social media should begin with dominating search engines.