Yes, this is not a joke. In protest of the Internet censorship bill SOPA, Wikipedia community had decided to make the website offline for 24-hours. Anyone who uses the internet knows how popular and how valuable Wikipedia is when you want answers to casual questions or research queries.
If it is going to affect your work, you can take steps so you don't lose access to the massive knowledge-base. Just Google "Offline wiki" and you will find several solutions to download the entire content of the Wikipedia to your personal device. These solutions are available on various platforms from Android to Windows. I think it's a good idea to have an offline Wikipedia anyway for those moments when you are not hooked up to the internet.
More information on the link below: