The world is a big place. And what's cool for one part of it may not be so cool for another. Take Diablo III, for example, which will have its violent content edited when it's released in certain markets.
In Australia and Germany, two markets where classification authorities (for varying reasons) run a tight ship, Blizzard will "have to change blood if [they're] going to sell there". We'd presume that means either tone it down or, like other games have done recently, change its colour.
For China, though...things aren't as easy. In fact, they're so hard the game may never be released there, Blizzard's Jay Wilson telling Wired "China's going to be hard for us. Because a lot of the restrictions there are really… we may not be able to do them. It may not be possible."