I haven't heard anyone say that Skype is actually blocked in China yet, but it's going to be a real pain if it is. My company use Skype for all its internal calls and I travel to China regularly.
This seems doubly odd when you look at posts like this:
Apparently Skype had a back door that allowed Chinese authorities to snoop on conversations. I wonder if Skype have now closed this and China is retaliating?