Here is a quick little article on Search Engine Marketing and the Corporate Blog:
SEM and the Corporate Blog

According to a Backbone Media case study (pdf), several blogs published by corporations produced the following strategic benefits:

• Public relations: Corporate blogs provide another way to publish content and ideas, get information to customers quickly, and receive customer feedback.
• Sales generation: With transparency heightened, corporate blogs can establish industry-specific thought leadership, build online user communities, and increase sales.
• SEM: Blogs can boost search engine positioning, increase link popularity, and readily allow for RSS syndication. All these add up to increased site traffic.