I'm not really a fan of copyright, especially the government-sponsored kinds.
But CC I'm happy with. Creative Commons solves pretty much every problem associated with copyright. I haven't looked into the duration of it, much, but I'll tell you this: As a writer, any money I make off my works after I'm dead does me absolutely no good. At that point, I'm feeding the scavengers in more ways than one. You know what? Screw the scavengers. I want to be remembered, not profited from. Making all my works public domain at the time of my death (or at least, execution of my Will) will make it that much harder for the scavengers to feed off my corpse, at least for very long.
Now, as to how copyright (even Creative Commons) could be upheld in an AnCap society, that's a different kettle of fish entirely. Basically, you would have to prove damages. Now, If I reprint your story, or artwork (or, since this is a webcomic site, both), without permission, I haven't really harmed you, exactly, but by not asking you first, I've cheated you out of the chance to ask for compensation. I think it would be fair to require that you have that opportunity after the fact, if I use your stuff to make any money.