Barry Schwartz writes, "Google has told us that Penguin is rarely refreshed, unlike Panda and we didn't miss any Penguin refreshes since."
Apparently some people thought there may have been unreported refreshes, and misconstrued something Google's John Mueller said in this Hangout:
The Panda is updated regularly, and much more frequently. The last one of those came last month, as Google announced on Twitter.
We're still waiting for Google to release its (what used to be) monthly lists of algorithm changes (or "Search Quality Highlights") for the past several months. They haven't done that since October either.
So far, Google hasn't really pushed out any earth shattering updates in 2013.