A directory with a blog is fantastic. Offering people a 300 word write up and a few deep links for extra money should benefit directories and webmasters. Most blogs use wordpress which has lots of easy SEO plugins that create a great internal link popularity/structure. This means each single post page has multiple links pointing to it with good anchor text; I think this plays a major part in generating link love in blogs. 'Traditional' directories only have one link pointing to each final link page and then has a one sentence description that is not likely to be unique. Basically, directories have a lot to learn from blogs. Just my 2 pence.