I first saw V for Vendetta when I was 14, almost 15 and I was mesmerized. It brought tears to my eyes and a part of my heart went out to the character V, even though the viewer I never saw his face, and only heard his voice. If you've never seen the movie you absolutely must. To be brief, it is about a masked vigilante who wears a mask that is modeled after the historical Guy Fawkes (who I will get to shortly). It is set in the future and in the UK where a totalitarian government has taken over and he is seeking vengeance along with the dismantlement of Parliament as it is known. The site IMDb.com says, "A shadowy freedom fighter known only as "V" uses terrorist tactics to fight against his totalitarian society. Upon rescuing a girl from the secret police, he also finds his best chance at having an ally." It fast became one of my favorite movies, ever. 
I didn't find out until about 2 years ago however, that the mask was a tribute to Guy Fawkes. I encourage everyone to do their own research on him since what there is isn't a whole lot and is easy to go through. "The short answer is this: Guy (alias Guido) Fawkes was one of the members of The Gunpowder Plot of 1605 in which a group of Catholics attempted to blow up the Houses of Parliament and kill James I, the King of England, to protest Protestant rule. As the man chosen to light the fuse and the first captured, Guy has received the lion's share of attention among the conspirators" (http://www.shadowgalaxy.net/Vendetta/fawkes.html). In Britain on November the 5th (Remember, remember, the 5th of November / The Gunpowder Treason and plot / I see of no reason why Gunpowder Treason / Should ever be forgot.) he is burned in effigy b/c over there he is viwed as a terrorist. But over here in America he's become quite the hero. Anonymous and Occupy have both adopted the masks because Fawkes was trying to take down a totalitarian government much like we are beginning to experience with our own...
SO. What does the mask mean to me? A lot of things. It represents freedom, strength, action, and desire for change; resistance. More recently it's begun to symbolize anarchy or voluntaryism to me. I wear his face proudly :)I see our country headed down a similar path toward something that Fawkes would have fought against, and what V is fighting in this movie (and original comic book). Wearing that masks gives me a sense of strength toward over coming the obstacles that the system in which I live has created.
I do not personally associate myself with Occupy or Anonymous I support them both at times, and other times I just SMH...but I have seen many wonderful "activist" pictures of people wearing this mask and gives me a sense of hope as well. Sure my generation is fully capable of being hooligans and just causing some ruckus, but I think we also share a lot of common ground and sometimes putting that mask on helps to breach that gap...
It is not for everyone, I realize that, but from the very first time I saw one of these masks I've been drawn to them...I hightly doubt that is going to change any time soon <3