Is there a public space on the internet, or just a series of private spaces we all perceive as public because they're available to everyone? People arguing against "censorship" online are often actually arguing for their "right" to say whatever they want in "public" spaces, but when every space on the internet, from Facebook to Twitter to your own blog is actually owned by someone (your blog is probably owned by Google, Wordpress or your web host) then there's no space where someone else doesn't have the right to take down what you say because they, personally, disagree with it. From that point of view, there might actually not be anywhere on the internet where the notion of "freedom of speech" even applies. There is nowhere you can say something online that someone else can't just say "no" to, and take it down again, no rights violated.
Mokalus of Borg
PS - I am not a lawyer, though, so don't take this as any kind of legal opinion.
PPS - I'm also not American, so the American Constitution, with its Amendments, does not apply to me either.