Whitey - 11:41 pm on Mar 21, 2013 (gmt 0)
Matt Cutts, Google's head of search spam, said on Hacker News, "we were tackling a spammer and inadvertently took action on the root page of digg.com."
Google released an official statement as well:
"We're sorry about the inconvenience this morning to people trying to search for Digg. In the process of removing a spammy submitted link on Digg.com, we inadvertently applied the webspam action to the whole site. We're correcting this, and the fix should be deployed shortly." [seroundtable.com...]
A timely example that errors do occur, but may not be treated equally unless you're a brand.