The co-founder of Moz, Rand Fishkin, posted on Twitter and also on the Moz blog that one of the YouMoz, the user generated content portion of Moz, contributors received a Google Manual action for a link violation and it cited an article posted on YouMoz.

Here is the violation notice as posted by Rand:

So this goes back to guest blogging being dead for SEO purposes. Which concerned a lot of YouMoz contributors, but Moz reached out to Matt Cutts and he responded via email that Moz should be okay. Here is a snippet of the email:

In this case, the anchor text was indeed keyword rich:

But each and every YouMoz post is reviewed by someone at Moz, so Rand is upset about this.

Danny Sullivan on Twitter pulled out more questionable things about this guest blog post:

Anyway, I did email Google about this and I may post something more detailed at Search Engine Land if/when I get a response. A shame Cutts is on leave, I wonder who will take the hit for this.

Forum discussion at Twitter.