Google has already made the general waves with its Google Panda algorithm update. The algorithm is updated every few months, and the latest jump to version 4 was a pretty big change (Google launched update 4.1 in September 2014). The core idea is that Panda helped to penalize web pages that were of poor quality. But, the latest update took the penalty to a whole new level.
Marketers have slowly followed the evolution of Panda over the latest three iterations. Version 4 added a new element for consideration. See, in the past versions, a specific web page was penalized. If the web page was not good (for a variety of reasons which will not be elaborated on here), the specific page was penalized. For example, a poor blog post about plants on an organic gardening site would be penalized. The website itself would not be, and that specific page will no longer rank well.
Version 4 introduced penalties to the entire website. Now, the poor page about plants would also count against the actual website. Theoretically, rankings for any page on the website would be affected. No longer is a poor page on an island of bad rankings. It affects everything.
The clear response to this now is not much different from the past. Low-quality content must be removed. Marketers could get away with leaving the bad content alone, and focusing on building great content in the future. With version 4, bad content from the past must be cleaned up.
The latest update also makes it harder to make a quick panda recovery. The bad content was penalized. It is removed, a recovery is sent in, and everything is fine after a day or two. Now, marketers must get the penalty removed from the website, and that brings forward a slew of new problems. In an effort to rid of the penalty from the whole domain, Google may notice other issues worth being penalized for. Without the proper set-up, and a proactive spirit, a penalty could accumulate. Get a thorough recovery from the actual domain, and not just from the specifically penalized web page.