From the petition site:
Just the other day, President Obama urged other countries to stop censoring the Internet. But now the United States Congress is trying to censor the Internet here at home. A new bill being debated this week would have the Attorney General create an Internet blacklist of sites that US Internet providers would be required to block.
This is the kind of heavy-handed censorship you'd expect from a dictatorship, where one man can decide what web sites you're not allowed to visit. But the Senate Judiciary Committee is expected to pass the bill this week -- and Senators say they haven't heard much in the way of objections! That's why we need you to sign our urgent petition to Congress demanding they oppose the Internet blacklist.
http://demandprogress.org/blacklist/