Google Penguin 2.1 is launching today, according to a tweet from Google's Distinguished Engineer Matt Cutts.
The first update to the second-generation Penguin algorithm designed to target web spam will affect "~1% of searches to a noticeable degree."
Google Penguin 2.0 went live on May 22 and affected 2.3 percent of English-U.S. queries. When it launched, Cutts explained that while it was the fourth Penguin-related launch, Google referred to the change internally as Penguin 2.0 because it was an updated algorithm rather than just a data refresh.
"It's a brand new generation of algorithms," Cutts said in May. "The previous iteration of Penguin would essentially only look at the home page of a site. The newer generation of Penguin goes much deeper and has a really big impact in certain small areas."
This is Google's fifth Penguin-related launch.
Google originally launched the algorithm that was eventually become known as Penguin 1.0 in April 2012. There were two refreshes last year: in May and October.