First off, I think comparisons to other governments & countries in order to prove the point that "at least we aren't this bad" is not productive.  Each situation is bound to be unique and thus not entirely comparable, plus, just because it's been tolerated before does not mean it should be tolerated again.

Secondly, no one doubts our past.  But Guantanamo, secret prisons thrughout the world used for torture, mass ... not even targetted, but mass surveilance (which has much different psychological repercussions) ... no fly lists, Patriot Act ... these things are new and their implications cannot be brushed aside using the assumption that we have continuously marched forward toward progress so nothing can be as bad as the past.  

Note, in each of the previous instances you mention, a particular group is the "enemy": Japanese, Socialists, Peace groups, Hippies, Democrats, Communists.  What we see today is different and I believe even more dangerous because aside from the Al Quaida, which we must all admit represent the slimmest of minorities in America, if there are any in the country at all, everyone is held under suspicion.  

You might compare it to McCarthyism, but I'd remind you that that was one man with an agenda and he was brought down easily enough.  We are now talking about the enactment of laws, the Executive branch, the military, the media and private corporations actively taking part in police state tactics without our knowledge and with few or no ways to stop them.  

Those who can make you believe absurdities can make you commit atrocities. -Voltaire