Google rolled out their latest algorithm update, nicknamed Penguin, on April 24th. I haven’t seen an update that has had this severe of an effect on sites since Panda. The blowback from SEOs, however, seems even more intense than Panda. This open letter to Google is one example.
While the majority of the sites I own were unaffected, minimally affected, or positively affected, many of the sites I monitor, but do not own, seem to have been hit hard.
Here is a pretty good rundown of what Google targeted with their latest update. Basically, they were looking to combat webspam in the form of low-quality comments, keyword stuffing, using money-term anchor text too often, and getting links in spammy ways such as commenting on a blog with your username disguised as anchor text that links back to your site.
The results are quite interesting. Websites that saw their search rankings tumble had a money keyword for anchor text in 65 percent or more of their inbound links, according to Microsite Masters (not that this percentage was a guarantee of being hit by Penguin):
Matt Cutts provided a link to a form you can use if you feel your site was unfairly and adversely affected by Penguin, though I doubt submitting your info will accomplish anything.
I will update this post as I learn more about it.