FYI: I was recently in China for a couple of weeks, and I found that neither the website nor the servers were accessible in two separate cities in China. When I was in Hong Kong, the website and servers were both accessible. Since mainland China is behind the Great Firewall (Chinese web censoring) but Hong Kong is not, I suspect that the nerd.nu domain is blocked by the Great Firewall.
I'm not sure why the site is blocked, but I have a theory: URL filtering. "Nu" in French means naked, so the censors might think that this is a site that contains a bunch of naked nerd pictures or something.
Oddly, the proxy server tests that allow you to see if things are blocked behind the Great Firewall indicate that nerd.nu is ok, but they aren't the most reliable tools (a couple of other websites that were not available in China pass the proxy tests). Also, other Minecraft servers were available, so the problem is not censoring of Minecraft servers.
