Weibo and Weixin are incredibly popular. But middle class intellectuals who want to prove their western credentials will generally have a facebook account. VPNs and proxies are fairly common, so access isn't really a problem, its just a hassle.
I have a free Amazon EC2 VPN that's also acting as a Tor Bridge. Over the past 4 years, between Tor and my personal VPN, I've never once been blocked in China.
If you want facebook on your phone, you'll need to setup a L2TP VPN, since China Unicom blocks PPTP. Instructions can be found here:
https://help.ubuntu.com/community/L2TPServer
NOTE: A bridge is not the same as an exit node. Exit notes attract attention from authorities, not bridges. If you are just running a bridge, you are only helping people circumvent government firewalls to join the Tor network. The default EC2 Tor Cloud images only run as a bridge.
You can always use Tor to set it up from home. I was in China when I setup mine. Since I returned, I never had an issue accessing it from any ISP in the states.
