A few highlights, not the whole talk.
My notes for the talk were the four words: novelty, reciprocity, frequency, mobility.
For novelty I spoke to the notion that people are on a perpetual search for the next new thing, and that any solution to any problem has to be revisited periodically in the light of this.
Reciprocity is the notion that people will respond in kind if you act generously to them, and I spoke to how this plays out in social media with "friends" and "followers" and "likes" as the actions often reciprocated.
Regarding frequency, the notion is that communications media have a natural rhythm, and that you need to be aware of how often you post or comment so that you don't either overrun the medium or be so quiet as to be unnoticed.
Finally mobility is the observation that more and more people are coming to the net primarily through mobile devices and if you want to serve them you need to have a solution for your web and net presence that looks good on the small screen.
I was greeted with a fair degree of skepticism about the value of social media for business, especially from someone who cancelled his Facebook account and never has been on Twitter. There was good discussion of how hard it is to simultaneously be brand-conscious and be aware of a professional persona vs. sharing details of a personal life. I think it's harder for people in an agency role whose job it is to make the client look good but who don't have to have a personal public identity in order to do their work.
Some day when I retire I'll give up on social media entirely and just send postcards to people - they are novel compared to the communciations that people mostly get, they're quite portable and mobile, no one expects a frequency of a postcard more than once in a long while, and if you send postcards you're likely to get postcards in return.