yaix2 - 2:05 pm on Sep 26, 2010 (gmt 0)
Under "account activity" -> "details" there is an option to "Show an alert for unusual activity".
I guess not only from China but anything that does not fit normal activity patterns of the account.
And not only Google does this. I got my eBay account blocked because once I forgot to turn on the VPN before signing in. Will have to call them to re-activate it.