A WebmasterWorld thread links to some comments left by a Googler at YCombinator.com named moultano. This Google warned of big changes coming to Google really soon. SEOs and Webmasters take this as a sign to be prepared for something major.
Moultano from Google said:
At the organizational level, Google is essentially chaos. In search quality in particular, once you've demonstrated that you can do useful stuff on your own, you're pretty much free to work on whatever you think is important. I don't think there's even a mechanism for shifting priorities like that.
We've been working on this issue for a long time, and made some progress. These efforts started long before the recent spat of news articles. I've personally been working on it for over a year. The central issue is that it's very difficult to make changes that sacrifice "on-topic-ness" for "good-ness" that don't make the results in general worse. You can expect some big changes here very shortly though.
Another comments left by this Google read:
We're not blind to the fact that a lot of scummy sites run adsense, but the even scummier ones have already been kicked out of adsense and now use other ad networks or affiliate programs. "Denying spammers revenue" has been at times the explicit goal of projects that launched.
Now, I do not expect Google to be releasing a filter on AdSense publishers. It wouldn't work too well, there are too many quality sites with AdSense. I do suspect the content farm algorithm to be released soon and possibly that is what this Googler is talking about.
But like Google knows, AdSense did not help reduce spam, it likely increased the spam out there. But in hindsight, banning the AdSense publishers won't stop them, they will just look for other avenues to spam and make money.
In any event, be prepared for the next major Google change.
Forum discussion at WebmasterWorld.