1. A method in a content recommendation system, the method comprising: identifying a news story about an event, the news story including multiple related content items that each give an account of the event and that each reference multiple entities or categories that are each electronically represented by the content recommendation system, comprising: processing content items to determine semantic information that includes identified entities and relations between the identified entities; storing the identified entities and relations in a repository of the content recommendation system; generating a cluster that includes the multiple related content items, based at least in part on how many entities each of the multiple related content items has in common with one or more other of the multiple related content items; and storing an indication of the identified news story and the generated cluster.