Chris Brogan has been writing up a storm on social branding and any of us can learn a good deal by following his series on it. But I have to admit that I have a basic disagreement with some of his observations in his most recent post.
He writes: "personal branding is noise. It’s talking about one’s self instead of talking about something that’s useful to others. But another way you might look at it is that personal branding is leverage: once you know me, you start to build a relationship with me. Once we have a relationship, I can share even more with you."
Although I believe in Chris's intended outcome, that personal branding let's you share more. But he takes a more transactional view than I do. I do not consider good branding--personal, product or corporate to be noise. I do not believe personal branding is the act of talking about one's self.
In contrast to Chris I believe that talking about others is a better way to build personal brand than the shameless self promotion of which so many of us are sometimes guilty.
A brand seems to me to be an emotional thing. It's about how people feel about you, your company or the products and services you represent. If I blog about things that are useful to you then it should increase my esteem in your eyes. You might share it with someone else and thus increase your own personal brand.
In social media, it seems like the people who give the most valuable or interesting information establish the strongest brands. They become trusted sources. The trust of others builds influence. Your personal brand may or may not help your employer. But what makes it personal is that it moves around with you wherever you go.
The irony is that Chris is someone with very high personal brand because he keeps contributing on social media subjects that matter to many of us. This includes the series he just did on personal brand. He has great influence on such topics. If he changed subjects to say--hummingbirds, it would be a nick in his social media and worse, he has very low clout among hummingbird enthusiasts--which brings me to my second point.
You personal brand also shapes what you know about and write and talk about. It shapes who you select as friends and credible sources. We social media enthusiasts determine each other's personal brands in we rarely do it when the speaker is discussing himself rather than issues valuable to ourselves.
Chris Brogan's personal brand is shaped more by what he writes on his blog posts then by what he has labored over on his About page.

