1. A computer implemented method for identifying trending topics on social networking services, the method comprising: obtaining a plurality of social communications posted on one or more social networking services; extracting a plurality of links from the plurality of social communications, each of the plurality of links corresponding to a different linked content; and for each of the plurality of links: categorizing the linked content according to news or non-news; and retaining the links to linked content categorized as news; determining a set of potential topic descriptors for the linked content; selecting a topic descriptor from the set of potential topic descriptors; and storing the selected topic descriptor as a trending topic.