@philjohnson has written an article for Advertising Age which cites one of my favorite books, The Innovator's Dilemma, and applies its model to Twitter as the disruptive technology. Here's the important part of the article:

"The bright light for agencies is that they can use this time of transition to make their organizations a proof-of-concept for social networks. They should be able to demonstrate how they have developed their own brand on Twitter and other prominent platforms like Flickr, YouTube and SlideShare. That they have created multiple touch-points for sharing content. That they have built a network that connects all their important audiences. And that they are accessible and open to honest conversation with all the people who want to engage."

Now, the not-so-bright light. Do we really think that very large advertising agencies can turn this quickly? I leave that to the Twitterers to decide.