I don't talk much about XRepublic these days. It's still a great idea but I don't exactly know enough about how to get it made. I don't have the time or the money and I don't see how I can get it at the moment. But I do recall a problem that I had with the entire system that required me to think about how to create the right way of categorizing the interest groups, resolutions and debates. Now, I think the answer is clear thanks to a presentation made by Clay Shirky (from the good old panix.com days) at Long Now.
Short answer. Tagging is a 'degenerate' form of categorization. It uses the power of social thinking about information. What millions of people think of something is a better way of getting to it than what a few experts think of a thing. The experts might be right, but the way people think about something changes over time and you need to follow that path.