Don't underestimate the US population's apathy. Until something directly affects us (as in, costs me money, or keeps me from angrily driving an SUV around, or keeps me from buying tons of crap I don't need) it's very difficult to enact change.
That said, I'm still going to the RestoreThe4th protests tomorrow. I believe in what this country used to stand for, and it's worth the fight to get it back, even if the rest of the country drowns in lethargy.
I wouldn't go that far yet... Signing an online petition is about the least you could possibly do, aside from nothing. If we want real change, we need major protests, people to flood Congress with calls & letters, and more. That being said, I think people are starting to do those other things, but major policy change won't come from an email on a petition.
That's the exciting thing about Restore the Fourth: real-world protests as well as online. We'll see how big tomorrow is, but in any case there will be a lot to build on.