Over this weekend, it has been confirmed by a number of people on Twitter, including Zineb Ait Bahajji (in French), Gary Illyes and John Mueller of Google, that what webmasters were seeing was not a Penguin update like we were expecting, but a core ranking algorithm update instead.
There were some early signs of an update that was noticed by Barry Schwartz of Search Engine Land, which he had called a “massive update” over the weekend. This assumption was later confirmed on Twitter by Google that it was indeed a core ranking algorithm update.
This is a rare occurrence that Google that they would confirm a core algorithm update, so this is a pretty big deal for them to admit so openly that the update everyone was seeing was core update related.
The Penguin update is still being waited on by Webmasters, and it is currently expected to be pushed this month.