Many web sites are closing their operations due to SOPA that are now being reviewed by the US Congress, including Wordpress and Wikipedia. They are two of many web sites that disagrees with SOPA along with many other organizations around the world.
It seems that if this bill is passed, the US government will have an ultimate power to control many web sites and behave like China's great firewall. We will have to wait until the review process is done and see the results.
For those who wanted to prepare for the worst, please have a look on DeSopa (DNS Evasion to Stop Oppressive Policy in America) plugins for Firefox