[Keios]

The point of Pareto's rule is not so much that the numbers must be 80 and 20. The essence of what Pareto proved is that the few(causes) are responsible for the many(effects). So Pareto's principle is very much at work in Flickr.

[ahsonwardak]

I agree with this point, and it what I intended. The key to the Pareto rule is that it should drive personal effort. For sites like Facebook, I think that you would just attract the content drivers (the 20%), and then the other 80% follow.

Think about it in terms of the Tipping Point. Go to the mavens/connectors first. They have all the knowledge know everyone. They'll do the buzz marketing for you and persuade others to join. Another term would be early adopter. I know that I have personal done this for Meebo.

[menloparkbum]

The "Pareto Rule" specifically refers to an 80/20 ratio.

Pareto didn't prove anything, he just made an observation about the italian economy. Other people noticed the ratio elsewhere, and named the rule after him.