One of my many search and social conspiracy theories (of which often turn out to be true) is that the Penguin algorithm update on April 24, 2012, was actually two updates. There was a public update that went after low-quality links, splogs, and other SEO linking tactics. This sent shockwaves through the search engine optimization world. Most agencies had to change some of their practices. Some closed down altogether. It was the SEOpocalypse for many in the industry.
The idea of the NoFollow attribute on links was to help prevent spam from appearing on user generated content sites, particularly Wikipedia. It was intended as a way to tell Google (and eventually all major search engines) that a link was not supposed to transfer any “link juice” to the recipient of the link. In essence, it was designed to stop SEO spammers from trying to insert their links where they didn’t belong for the sake of improved rankings.
Update 2: The site is back up and back to 20-minute update intervals.
Update: Digg sped back up to its normal pace for a little while, then went down completely. API calls and everything are currently down.
For over 12 hours, the Digg front page has moved at half speed. Instead of the normal 10-minute interval between updates, stories have remained at the top of the front page for 20 minutes.