Hummingbird is the biggest iteration of the Google algorithm since Caffeine in 2010. It is, however, going to have less impact immediately on search marketing than the Panda and Penguin updates. Amit Singhal, of Google, said 90% of searches have been affected by this algorithm change.
The details of the Hummingbird amendments are provided below, detailing what has changed and how it impacts search marketing strategies.
http://www.sitepronews.com/2013/11/15/googles-hummingbird-update-significant-businesses-think/
Toms Blog on Life and Livingness