I'll do an article on it one of these days but basically the point system is to allow articles to get attention based on some sort of merit and not the whims of some admin.
When I started the site, I was frustrated at the seemingly arbitrary way that the "big" blog sites would link to other articles. I'm a believer in democracy and so if enough people say "This article is interesting", respond to them, etc. it will get more points which will help it float to the top in the various JoeUser lists.