Yes, it really is important.
You can read about it here. And take a look at this NYT article.
Note that the Wikipedia page on SOPA is not blacked out today.
Spain's El Pais covers it here. BBC has info on it here.
I would like to mention that I am a respectful observer of copyright. In fact, just yesterday someone asked me for a copy of the sock pattern I use. I gave her the name of my favorite pattern and told her where she could purchase it, which she did. I don't copy stuff, I don't distribute things to circumvent purchasing them, I don't make money off of other people's property, intellectual or otherwise.
I am against SOPA though.
The First Amendment is worth protecting. Pay attention. This whole thing about protecting piracy with perhaps a little infringement of First Amendment rights reminds me of the fascist ladies in Chile who marveled at the safety of the streets during the dictatorship. Yes, Santiago was safer than Caracas then, but at what cost?