It's not clear to me if it's just that Google can not be be reached from China, or also that email from Gmail to .cn email addresses is also somehow blocked. My take is that they can not reach their Gmail accounts, but would be also to get email from you if you are sending to a .cn account.
Just an update that my company has been using googleapps (domain gmail mainly) in China.
And the quality still sucks elephant balls. Like 1mb email taking hours to send / receive.
Wouldn't use it if I knew it's going to be like this. I am pretty sure it's a gmail issue as we have no such problems with the email server(outside of China) when users in China access it.