Several companies that have had more success that others regarding promoting their products via blogs have successfully implemented the six following steps...
1. Search common web portals to see if a popular blog already exists on your company's product. (i.e portal.eatonweb.com)
2. Look at frequency of blog to ensure that it is posted on at least TWICE a week.
3. Ensure that this blog is cross linked across the internet community (check technorati.com)
4. Read bloggers entrees to see if the blogger would be amenable to an outside approach of blogging about your companies product. Only use this approach if the blogger seems enthusiastic and develops a positive attitude towards your product.
5. Ask whether the product of service is applicable to blogging. Are there already extensive web communities developed around your product. I.E new camera technology works infinitely better in this medium than say new milk products. Some products generate more technical interest on the internet, particularly products that develop and update quicker than others.
6. Use convetional means to promote the blog. These could include e-mail, online and print advertising, television, and promotional sweepstakes (giveaways) reguarding the blog.
Reference: Marketing And Blogs: What Works by James L. Horton