From:
This presentation, available at slideshare, was made at Strata 2011 Conference by Kevin Weil @kevinweil, Product Lead for Revenue, Twitter.
Kevin talks about Rainbird, the distributed system Twitter built on top of Cassandra, a highly scalable, distributed structured key-value store, and gives a number of examples how Rainbird is used to analyze tweets.
www.slideshare.net/kevinweil/rainbird-realtime-analytics-at-twitter-strata-2011