iPhones in Beijing???

I am moving to Beijing in August and was wondering if iPhones work in Beijing? What kind of "iPhone" type phone (the one with 3G, google translate, iTunes, maps, internet, etc.) is most common. Are those types of phones cheap to buy in BJ or should I get one from the States? Will a phone from out of country work in BJ? Does they just take a BJ SIM card? Please advise. Thanks.
Marty