VPN in China
One of the biggest countries in the world, with one of the longest histories on Earth, is also home to the one of the strictest policies on Internet censorship.
Despite the fact that Iran, Oman, The UAE, Laos, Singapore, and many other countries censor the Internet (Even the USA does to some extent), China is the country that everyone's looking at, like Big Brother in some 60's novel about government control.
It's crazy how much they block. I lived in China for 5 years. At first, websites like Facebook being blocked was a novelty. Soon, it became a nuisance, and by the end of my stint in China, I just had my VPN connected 24/7 and didn't even bother with trying to use a Chinese IP.
In March of this 2011 we saw a few of the VPN giants like Freedur and Witopia take a nose dive and got blocked temporarily when China's government infiltrated their sites, found VPN servers, and blocked IP addresses.
For a while there we thought China was going to block all VPN's. However, most recovered since then there hasn't been much of a problem (but Witopia's still down as of April).
UPDATE 2013: There was another outage of VPNs in Dec 2013 when they were electing new officials. It's since subsided, and things are back to normal…for now!
What China did succeed in doing is blocking PPTP and L2TP protocols which means that many of your mobile devices using these protocols won't work in China. They have since been unblocked. Now, OpenVPN is recommended for laptops and desktops, L2TP for mobile devices.
Update 2014: All's been quiet this year!
12VPN and PandaPow both experienced temporary blockings but we're still recommending them because of this – With Internet censorship as serious and strict as it is in China, you need a professional VPN service that's going to deliver when there's problems.
Both 12VPNand PandaPow came around and within days were able to come back online and provide superb VPN service to the Chinese people as well as Westerners in China.
Popular sites currently blocked in China
Facebook, Twitter, Blogger, Youtube, Linkedin, Google (sometimes), Foursquare, Technorati, Tumblr, + other blogging, social networking, and video sites, not to mention torrent downloading sites and MOST DEFINITELY religious, political, and educational sites.