So if I was a penguin… Google have rolled out Penguin 3.0 and topping the hit list are the low quality, spammy backlinks.
True to the nature of a Penguin you can view how this Google algorithm can pick up signals that will find even the deepest buried backlinks and how they deal with them.
Google have taken a year to update from Penguin 2.1 -3.0 and it will be a deep cleansing I imagine. Future plans are to roll out more frequent, less invasive updates.
There is always a way back if you have been sunk in the rankings and with good management of your Website there are ways to prevent it.

Enjoy the Penguin in action!