All this chatter about when Google will launch Penguin, will we know? Who will tell us? etc etc... Trust me, when Penguin launches, we will know.
But just in case you were worried, Google said they will announce it when it starts rolling out.
John said, "I am pretty sure when we start rolling out [Penguin] we will have a message to kind of post but at the moment I don’t have anything specific to kind of announce."
Here is the video embed with the start time set:
So far, I see no signs of a Penguin roll out myself.
Forum discussion at Google+.