I saw a great article on NYTimes.com that provided an overview of the current state of display targeting.  I think it overstates the difference in price for targeting however, “Advertisers are willing to pay much higher rates to reach such screened audiences”.  For example, CPM’s for behavioral targeted inventory are currently $1-2 more than those of specific channels within ad networks.  As advertisers and publishers realize the value of reaching people out of context, I could see these numbers changing, but that shift hasn’t occurred yet.