Another post on the banning/de-indexing of Digg by Google, datadial popped up on an SEO group with the 1st instance of this news and many posts have followed, read my related posts for more opinions.
Update 1800 20th March 2013
Matt Cutts reveals Google inadvertently de indexed Digg whilst tackling a spammer.
So, let’s look at the scenario,
Digg is no longer is indexed in Google:
Their robots.txt file didn’t exist earlier in the day, but no seems to have recovered so was this issue, not having a robots.txt or showing a 404 error for the file, Google may not index a site with an error of a robots file.
They have millions of links, 963,508,932 to be exact:, is it a link penalty, most unlikely: