Nice article from Ad Week about advertising in social networks, and how the model there is going toward building experiences instead of just display ads.
This fits well with what I wrote last week on the same subject.
The big question of course is how you measure the success of such campaigns, and how you compare one to another. This opens up again the discussion about engagement metric which I won’t dive in right here, but feel free to read other posts in this blog which discussed this issue 