It's not easy to buy and sell Bitcoins in China, as the central bank has declared that the Bitcoin is not a real currency and thus cannot be handled by banks. Since then the Bitcoin exchanges in the country have tried different solutions to be able to keep their business going and now we see the first Bitcoin ATM installed in mainland China.
The ATM has been installed by BTC China in a cafe inside a mall in Shanghai and allows people to buy Bitcoins for their Yuan. It is not possible to do cash withdrawals of your Bitcoins, but it has made it possible and easier for those who wants Bitcoins for whatever reason to get a hold of them without having to encounter problems with their bank.
While both OKCoin and BTC China have had worries about being shut down by the Chinese government, nothing has happened so far and thus they'll continue with their business. It is not illegal for individuals to buy or sell Bitcoins in China, but it seems that there will be coming some sort of law to out rule the usage of Bitcoins overall.