Matt Cutts wrote:
We just started a new ranking update today for some spammy queries.
It is not fully rolled out yet, Matt added:
It's a multifaceted rollout that will be happening over the next 1-2 months.
This specifically aims to target more spammy like industries where the link building and spam tactics are more extreme. Matt added more details while at SMX, which I covered at Search Engine Land.
Matt said that this impacts about 0.3% of U.S. queries but up to 4% or so of Turkish queries where spam is a larger part of the index there. Matt also added that the techniques targeted here are often "illegal" tactics that he won't discuss.
Matt discussed this in his video from a few weeks ago 2 minutes in 30 seconds in. Here is the transcript, followed by the video:
It’s kind of interesting. We get a lot of great feedback from outside of Google. For example, there were people complaining about searches like “payday loans” on Google.co.uk. So we have two different changes that try to tackle those kinds of queries in a couple different ways. We can’t get into too much detail about exactly how they work, but I’m kind of excited that we’re going from having just general queries be a little more cleaned to going to some of these areas that have traditionally been a little more spammy including, for example, some more pornographic queries. And some of these changes might have a little bit more of an impact in those kinds of areas that are a little more contested by various spammers and that sort of thing.