"BlogPulse Key Phrases, Key People, BlogBites, and Top Links are mined daily from new entries in over 750,000 weblogs using machine learning algorithms and natural language processing techniques. BlogPulse mines for bursty phrases and person names instead of for the most popular ones. The most popular phrases and names change very slowly over time. The burstiest phrases and names are those whose frequency of occurrence has increased significantly over the past two weeks, often dramatically."
BlogPulse: Automated Trend Discovery for Weblogs