Although I don't claim any expertise in marketing I do, increasingly, get drawn into conversations with clients about how to do it on the social web. Given my grumpiness about the way marketing has hijacked the phrase social media and turned it into so much less than it could be this is ironic!
However my position is always the same. Organizations Don't Tweet - People Do! The best way to market your product or build your brand is to be genuinely interesting and passionate about what you do. The best way to do that is to allow your staff to become more open about their work and get better at being your advocates online.
I am currently in the process of setting up my Google Authorship and was recommended this article by a friend. It explains the thinking behind Author Rank and the fundamental impact it is likely to have on how we find things on Google. This feels like a significant step towards my ideal of real people having real conversations about real products.