Blogs have no special powers in which they gain high rankings. Although if implemented correctly, they will contain fresh and unique content. Search engines tend to like that, regardless of the format. They know when a given site is adding new articles frequently, so they will index it often. Blogs are an easy venue for adding new information to your website. A similar benefit can be achieved if newsletters, press releases, or popular forums are are archived onto your site.
In addition, blog posts will also show up in blog searches such as Google’s Blog search, and Technorati Blog searches.