Though Facebook's (FB) core site and apps largely remain blocked in China, Instagram has been growing rapidly in the Middle Kingdom. The photo-sharing platform's iOS app is now ranked #66 in the Chinese App Store, and a number of Chinese celebrities have 100K+ followers for their Instagram accounts (largely from within China).
The widespread use of Instagram with the Weibo (WB) microblogging platform (129M MAUs) has fueled much of the growth. Instagram has added a Weibo sharing option for its apps, and its pictures are often used by Weibo posters to cover major events.
Bloomberg reported in May Facebook is taking steps to open a Chinese ad sales office, but there aren't any signs its core services will soon be given a green light. WhatsApp isn't blocked, but it faces an uphill battle wresting Chinese share from Tencent's WeChat.