How do Digg, Reddit, Netscape etc. Rank News Stories?

I just came across an excellent post by our neighbor just South of the 49th parallel. Basically there has been a lot of chatter recently about Digg, and other social network news websites. Let's ignore all the "good vs. bad" editor talk and manipulation and take a brief look at Rand's post from a purely algorithm perspective.

For those of you not familiar with Digg and the like. Let me explain why the SEO community cares so much. Basically these sites have a couple of major benefits.

They can drive thousands of visitors and generate excellent industry buzz (if your story gets promoted properly) – short term benefit.
They can create hundreds of quality back links which will help your site rank organically – long term benefit.

Lately there have been plenty of posts about how to write a good Digg story, so lets focus on the math.

Basically stories get ranked based on the following algorithmic criteria.

Number of votes over time
Domain of link
Profile of submitter
Profiles of voters
Timing of submission
Similarity to other links (duplicate)
Source of votes
Manual review as it hits the homepage
Number of comments
Number of views
Down votes
Source of Votes

Rand has gone in to more detail in his blog – read his full post here. I felt that this information should also be posted here as there has been a lot of discussion inside our company about Digg and their competitors, so I thought posting this might help clarify how Digg works.