Well, there we have it, folks, Google officially announced that Penguin is now live for all languages.
Google relies on 200 or so ranking signals, Penguin is one of the most important such signals and it was first published in 2012.
The biggest change in this latest Penguin update is now in real time, meaning webmasters don't have to wait for long periods of times anymore for Google to recrawl their pages to notice the changes and rank them accordantly.
The effect will take place almost instantly after a Google crawl, meaning you may get different ranks, good or bad, depending on your website's evolution since the last crawl.
The Google announcement also states that Penguin is more "granular" now, you may be wondering what the hell that means? Well as far as I can understand, Penguin in the past would review a website's spam score and rank the whole website based on how good the spam score was. Now, apparently each page has a spam score and if one of your pages has a high spam score that doesn't mean Penguin will penalize your whole website.
That's about all I could understand from the information provided by Google. I bet all SEOs will need extensive tests to figure out how to optimize websites at their fullest potential for Penguin 4.0.