PBS was after a new, younger audience.
In order to reach younger people (back in 2010), the idea was to give them a new way to see, and change how the news affects the world around them. By placing trending topics alongside the journalists who reported the news, readers could open a dialogue or watch one unfold to better understand the situations.
An intelligent navigation, specifically the predictive 'Trending Topics:' feature was desigend to rearrange itself to present the most popular content first. Essentially, the vibrant stream of content was automatically curated by the community that viewed it, and influenced by their conversations.