Target Marketing on Social Networks

I said it would happen, and even named it as one of the monetization strategies for online social networks - target marketing. Boing Boing reports that Myspace has gotten wise and they are directing adds to users based on .... shock ... their interests. What is so confusing is that we have not seen this surface yet. I wrote about monetization models well over a year ago. We went through the add revenue model, and the premium subscription model, and even saw the gift economy model. But seriously did it need to take this long to get to the real value of understanding a constituent and driving products to them based on their interests?