You are not supposed to be able to hit the url in your browser. You are supposed to use it as a gem source in a Gemfile or with the gem command line tool.
There is also http://gems.gzruby.org/ if you happen to be behind the Great Firewall of China
Thanks for the hint. I really didn't know that. I will update the blog post with my new knowledge. One point more for Bundler/RubyGems :-)