Somehow, I think that the incident with Shopzilla is related to the recent news that anyone using the PayPerPost method just got their PageRanks reduced this weekend.
Forum members have mixed reactions. Some have obviously participated in such schemes. Others hope that those who participate suffer the consequences:
If you cheat you die.
Google seems to be taking out all the "schemes" that were set up to game the system.
Finally, others note that they have been penalized without using any paid advertising at all. These forum members feel that their penalty was unjust and that Google should review why it happened to begin with. Personally, I've seen a lot of incorrect penalties over the past few weeks that Google has not yet rectified, even with a request for reinclusion. I understand the frustration there.
Forum discussion continues at DigitalPoint Forums.