There are many social media monitoring tools that discover the brand influencers on the blogosphere. Many brands use this to identify these influencers and invite them to either review thier product, their services, or invite them to an event so they can review it.

Thus, I found this very interesting blog post by Steve Rubel about the New Influencers. Its a good read.

http://www.steverubel.com/white-paper-engaging-the-new-influencers

I think that the importance of the new influencers is determined by your product offering and target audience. If you are targeting real niche markets with very high-end products and services the new influencers will be less of a factor than limited use version of your product or service so that the potential end-user can determine the value of the offering. But I am coming from the perspective of niche markets/nich products so I am skewed in my view.