Apparently it looks like some (or all) users in China are facing issues while accessing the Android Market, Gmail and Google Talk on their Android based devices.
A user on the Android Forums posted a thread today that he was unable to access Market, Gmail and Google Talk from China. According to the user the problems have been happening since 13th June and has been occurring in Mainland China.
Unfortunately, Android Forums itself has gone under so could not check the entire conversation, but here is the page on Google Cache from which the below screenshot has been taken.
The actual thread is here just in case you want to check the debate, however it is still down for me. Are you in China and facing the same issues?
Update: From the comments below we were able to confirm that China is indeed blocking the above services.