Idil Cakin of Burson Marstellar offers some good advice about dealing with the blogosphere in an article for DMNews. Excerpted below are some of the more interesting points. Whoever comes up with the best "secret sauce" to solve the problem of weighting blogs will have a powerful offering. (This is something the brains at CustomScoop are actively working on.)
Keep your hand on the pulse: Partner with online research firms that mine and analyze user-generated media to determine if and how bloggers are buzzing about issues related to your business.
Map your blogosphere: Survey your audience and identify those who actively write and/or read blogs.
Weight your target blogs: Develop quantitative and qualitative metrics to rank the most influential bloggers for your industry. When determining a blog’s influence, evaluate the types of links on the blog, frequency of content updates and the credibility of the blog author. Track key stakeholders’ awareness and reactions to the blogger’s entries.
(Hat tip to Steve Rubel.)