In my research I focus on user collaboration. Social networks are a fascinating phenomenon that expand the definition of collaboration.
Does the spread of social networking mean the end of the sales function? I doubt it, but if you are interested, another blogger makes that case:
http://nickpoint.co.uk/2008/06/26/the-death-of-salesmen-and-power-to-the-people/
I agree to a certain degree. I believe that selling nowadays has taken the salesperson out of it. I look at reviews before buying things instead of asking a salesperson of the store. But I very much doubt the salesperson will ever be fully taken out of the equation no matter how their role is lessened.