Wi-Fi capable iPhones have been blocked in China because of government regulations that require smartphones to support the country’s WAPI protocol — a protocol that ins’t included in the iPhone. With WAPI support added to the Chinese version, Apple can begin selling Wi-Fi enabled versions of the iPhone in the country.
Government documents indicate that China approved the radio frequency ranges for an iPhone model that also includes Wi-Fi support. With the addition of Wi-Fi, the model appears to match iPhones that are currently available through China Unicom.
Assuming Apple actually has build a WAPI-compliant iPhone, that should make it easier for China Unicom to compete with grey market sellers that have been importing iPhones with Wi-Fi enabled from other countries.