I choose to quote a friend of mine:
"To put it simply, SOPA hopes to end online piracy. This is mostly coming from the movie industry, and while a noble cause would have serious repercussions on the free web as we know it. In order to prevent online piracy, the bill essentially gains the ability to punish websites for copyrighted material that their users posted or for the government to censor entire websites.
This could be Facebook, Google, Youtube, Twitter Tumblr, Reddit and any other website around. (like blogger!) The only way to prevent that would be a moderation system, where every post would need to be checked for illegal materials and given the population of some of our favorite websites, they might as well just close up shop if the bill passes.
So if you're one of the millions who check your friends walls, or enjoy being able to "like" whatever you want, do your part and read up on what SOPA is and if you oppose it (as you should) sign the petition (which takes two seconds) to say you don't want SOPA to pass."