Best solution is a VPN, virtual private network.
Original application: Company has offices in two or more places, say NY and LA; you want employees in one office to access servers in the other. A few decades back, big companies did this with leased lines, building a Private Network. These are secure if either the phone company is trustworthy (often they are not, see for example
http://www.eff.org/issues/nsa-spying) or if you put a box on either end of the link to encrypt as it leaves one office, decrypt when it reaches the other.
A /virtual/ private network or VPN does basically the same thing but using the Internet instead of a leased line. Both offices have firewall machines; make those encrypt as it leaves one office, decrypt when it reaches the other. Now everything that passes over the Internet is encrypted, so presumably secure.
The other VPN application is the "road warrior". Your sales person is somewhere with a laptop; make that laptop encrypt/decrypt and he can access the corporate network securely.
That's basically what you are buying when you get a VPN service; your machine acts as the road warrior and they provide one or more servers you can connect to securely. Those servers then connect you to Facebook or whatever. The server-Facebook connection is outside China, not censored.
Everything passing through the Great Firewall is encrypted, so they cannot censor it short of shutting down the connection entirely. I'd say they are quite unlikely to do that since most companies rely on VPNs.
Of course the devil's in the details and there are lots of details here, but there are standards (IPsec and SSL/TLS) that have been carefully designed, extensively tested and thoroughly analysed, so there's some hope of getting it right.
I'd use Witopia (
http://www.witopia.net/welcome.php) basicaly because ther "about" page says "Founded in early 2003 by former UUNET Managers, ..." and I know UUnet. I'd pick their $60/year SLL VPN because I trust SSL much more than PPTP.
There are many other vendors with a range of prices and features and Witopia have other plans from $40/year to $200 for the hardware then $99/year.