People buy from people – more specifically, people buy from people they like (and trust) – this is one of the first lessons of sales.
100 years ago it was very difficult to have relationships with anyone outside of a few people in your neighborhood. Many people lived on farms and only rarely did people travel outside of their local town.
Today I can post something on the Web and within a few hours I can have started conversations with dozens of people.
This illustrates succinctly one way in which blogging can empower businesses – it extends the reach of the company by building relationships and creating dialog with an interested readership. Over time the blog author establishes their credentials with their readership and if they are blogging on behalf of a company (and blogging well), the readership will come to trust the author.
This trust and the relationship which has built up between the blogger and his readers means that the readers are more likely to purchase from that company.