I m not saying PRISM is lawful (that remains to be seen?), but i think many non-US citizens are feeling too entitled to the protection of US law.
It's seems stupid that given recent events that the uproar over whether the US government is reading your Facebook posts has rammed the point home to many people but I guess this is just the final prod that woke a lot of people up.
*Purely from the perspective of the government. I've nothing but admiration (mostly) for large parts of the culture, attitude and hard work of the good citizens of the 50 states.
There have been at least four or five major epochs for the US, which saw fairly substantial changes (good or bad) to the rule of law and social cohesion. We started as a constitutional republic and nearly laissez-faire capitalism; then we had a massive federal explosion post civil war, that saw the power of the states greatly diminished; we shifted to a mixed economy, welfare state with a heavy bent toward democracy; now we're speeding toward police state socialism with oligarchs, the facade of property rights, and blended government-corporations, aka fascism (or as some call it in our incarnation, corporatism).
What you have to realize is that 4th Amendment law is largely tied to searches for prosecution reasons and so usually the issue is "well, the 4th Amendment is violated and so to punish the government and give them the right incentives, we won't let them use the following set of evidence in their prosecution." It's really hard to make such rules effective regarding surveillance of foreigners conducted overseas.
Non-citizens in the US for whatever reason do have relevant liberties. This does not extend to say buying tv advertisements for candidates in elections, but it does extend to unreasonable searches and seizures. Non-citizens with no real ties to the US, and not in the US are different.
But their US property is still protected. If I'm a Russian orthodontist in Minsk and I buy 500 shares of Google, the Fifth Amendment protects me having them expropriated by the US government even if I never go near the States. (IANAL, but I did check this one.) However if I open a Google Mail account then apparently (under current interpretations) I have no similar protections.
I can't say if this apparent discrepancy is actually legally justified, or not. Without even getting into the question of whether it's morally justified, it is going to come as a significant surprise to a lot of people, who have got used to the idea that they're largely protected by the US rule of law when they do business with the US. And one way or the other, it's reasonable to point out that Rackspace's Fourth Amendment-based reassurances seem to be (no doubt accidentally) crucially misleading to many or most of its customers.