Wikipedia is going to go dark for 24 hours in protest of litigation its founders believe compromises the openness of the internet and availability of information. Their explanation here is here. A brief message with the opportunity to look up (if you don’t already know) your Representative and Senators to contact them is on their main page.
CNN has more on the story here.
Politico has an explanation of the Stop Online Piracy Act (SOPA) and the Protect IP Act (PIPA) here.