Digg Restricts Chinese IP?

I took a look at Digg this morning and read a nice article, then I suddenly had the urge to digg. So I tried to log in, but found that I couldn't - it prompted me: Sorry - bad IP address. Here's a screenshot:

It seems like I can only be a bystander on Digg from now on. The reason for Digg's IP restrictions in some areas is still unknown, but here's my guess.....