According to a new study conducted by social media analysis firm BuzzLogic and JupiterResearch, more than half of blog readers said that blogs influence their purchase decisions. It also found that of those readers, 56% are influenced by blogs with a "niche focus and topical expertise", and a further 40% have taken action after seeing an ad displayed on a blog.
So what can we conclude from this? Internet users place trust in what bloggers have to say, especially if the blog content provides them with useful, valuable information that allows them to make a sound purchasing decision. They see bloggers as experts and authorities in their fields, and even go so far as to trust the blog's sponsors (authority by association).
This isn't to say that businesses should exploit this trust by sticking up a blog and posting any old piece of marketing fluff or keyword-stuffed article. Trust is most definitely earned, so your blog still has to establish itself as a "go-to" for trustworthy, authoritative information.
Check out this post I recently contributed at Justin Levy's That's Great PR blog. It'll give you a good idea about how to develop engaging, authoritative content:
Content is Nothing if it’s Not Authoritative: Creating an Effective Content Strategy