After saying they tend to not release updates during the Holidays, Google released 3 updates in a five day period last week, not to mention the one on Thanksgiving day (Happy Holiday's *sigh*)

Penguin 1.0 on April 24, 2012 (impacting ~3.1% of queries)
Penguin 1.1 on May 26, 2012 (impacting less than 0.1%)
Penguin 1.2 on October 5, 2012 (impacting ~0.3% of queries)
Penguin 2.0 on May 22, 2013 (impacting 2.3% of queries)
Penguin 2.1 on Oct. 4, 2013 (impacting around 1% of queries)
Penguin 3.0 on October 17, 2014 (impacting around 1% of queries)
Penguin 3.1 on November 27, 2014 (confirmed by Google, no impact given, Google considers part of Penguin 3.0)
Penguin 3.2 on December 2, 2014 (not confirmed by Google but based on publisher reports)
Penguin 3.3 on December 5, 2014 (not confirmed by Google but based on publisher reports)
Penguin 3.4 on December 6, 2014 (not confirmed by Google but based on publisher reports)