Recent rumors that Google has been releasing Penguin updates unannounced has search engine experts up in arms. A recent Hangout video of Google's webmaster John Mueller lead many to believe that this was the case. However, the tech giant has denied those claims. The last confirmed update was in October 2012, which was the third Penguin update.
Penguin, an anti-spam filter employed by Google to help determine a website's relevance and legitimacy, has a powerful effect on site ranking and is something that all online marketers should keep in mind. The fact that updates may occur without being announced is a scary thought to many. Mueller made a statement that led many to believe Penguin is on a regular updating cycle, but Google has since confirmed that he was referring to general "link analysis," according to Search Engine Land, as opposed to the algorithm. It was also stated that the algorithm hasn't been changed since it was last announced in October 2012.
On the other hand, the Panda algorithm is updated monthly. The next version has not been confirmed, but based on previous refreshes, a new Panda update is set to arrive shortly.