Audience Targeting vs Site/Category Targeting

Interesting comment from a recent Adotas blog post regarding targeting people instead of pages:

In a recent eMarketer study, 90% of advertisers said they plan to use ad networks in the coming year and the top two factors that they will use to differentiate networks were the quality of inventory and the audience targeting. Networks that have quality inventory and rich audience targeting capabilities should be some of the first places marketers and agencies look in 2009 and beyond to keep revenues flowing at lower costs and greater efficiency.