This is a 24 hour blackout to protest the proposed Stop Piracy Online Act (SPOA) and the Protect IP act (PIPA) in the United States. This blackout was inspired by Wikipedia's blackout. If it's enough to put the wind up Wikipedia, it's enough to have at least a disturbing zephyr blowing me.
Now the details of this are pretty complex. I suggest looking them up on Wikipedia... Oh wait... Umm, I suggest going into a trance and channeling the information from the gestalt consiousness of humanity. No wait, don't do that. You'll probably end up with a mind full of viruses and pop-up ads. And if I've learned anything about humanity from the internet it's that humanity's racial unconsciousness probably consists of a sabretooth tiger saying, "Can I haz mammoth cheezburger?"
Anyway, although I don't have as good a grasp of the issues as I'd like, I think there is a good chance that the US is stabbing themselves in the foot with this one. And this is stupidier than shooting yourself in the foot. It's actually not that difficult to accidently shoot yourself in the foot, but stabbing yourself there takes effort. You see, America is full of people who hate their jobs, but who are willing to work online for free and produce all sorts of neat stuff such as Unix, Wikipedia, even youtube videos (some of them are actually good, or so I've heard). I think anything that damages people's ability or likelyhood of doing this is going to hurt the economy of the US and thus the world in the long run. And it may also reduce the 'soft power' of the United States if this makes the US less relevent to the rest of the world. The mildly extreme scenario where US citizens more or less lose access to Wikipedia is a situation in which the US has less influence on the world.
I expect there will be future changes to how online interactions are regulated. I just think it would be better if the changes had a higher chance of helping rather than hindering.