Update from Matt Cutts: Matt clarified and gave a lot of context to what he said at SES SF. Here is his comment:
Hey Barry, I wasn't saying that people needed to overly stress out about the next Penguin update, but I'm happy to give more details. I was giving context on the fact that lots of people were asking me when the next Penguin update would happen, as if they expected Penguin updates to happen on a monthly basis and as if Penguin would only involve data refreshes.
If you remember, in the early days of Panda, it took several months for us to iterate on the algorithm, and the Panda impact tended to be somewhat larger (e.g. the April 2011 update incorporated new signals like sites that users block). Later on, the Panda updates had less impact over time as we stabilized the signals/algorithm and Panda moved closer to near-monthly updates. Likewise, we're still in the early stages of Penguin where the engineers are incorporating new signals and iterating to improve the algorithm. Because of that, expect that the next few Penguin updates will take longer, incorporate additional signals, and as a result will have more noticeable impact. It's not the case that people should just expect data refreshes for Penguin quite yet.
As you know, many SEOs are eagerly awaiting a Penguin update but Matt Cutts, the head of search spam at Google, said "you don’t want the next Penguin update." He warned that the Google "engineers have been working hard," on this update.
He even added the next few updates will be "jarring and jolting" for webmasters and SEOs.
I've never seen a warning like this before from Google. It makes it sound like the Penguin update will be felt by many many more SEOs. Our initial poll said about 65% of SEOs were hurt by Penguin - why so many more than Panda which was 40%? Well, this is aim more at SEO techniques despite what Google wants to say otherwise.
Honestly, if Matt is saying this, I wouldn't blame anyone if they are a bit worried.
I wasn't at the talk, many were and the feedback coming out of it is that Matt was sincere about it. Again, I was not there, so I can't be certain.
In any event, make sure to brace yourself for the next Penguin update!
Forum discussion at WebmasterWorld.