What is the latest Google penguin update?
As per matt cutts blog last update was penguin 2.0 and it was updated on May 22nd. Google always try to display quality result to their users. This is the reason to update algo frequently time. If you doesn't want to get penalize then always approach with white hat tactics.
This can be a fourth Penguin-related launch Google did, but because this is a great updated algorithm, we’ve been talking about this change as Penguin 2. 0 internally.