I don't think the issue is as much technical as it is about the nature of the community. digg, reddit, hacker news, etc. all have similar features, but quite di

I don't think the issue is as much technical as it is about the nature of the community. digg, reddit, hacker news, etc. all have similar features, but quite different communities. these communities are generally molded by where they exist in the mind of the user, which can be influenced by the UI. HN only allows up-arrows to create a positive slant, reddit has a functional looking UI for a technical slant, and digg aims for a mainstream look. This is why facebook, twitter, and google+ aren't necessarily direct competitors, because they are all designed to scratch a slightly different itch.