Americans have traditionally maintained a claim on the right of expression. In fact, it can be argued that it is that right that is the premise for all our other liberties. However, the right of expression has always given way to the right of existence - in other words the right to be protected from harm. So, when "An unprecedented security blanket will be draped across San Francisco for the US leg of the Olympic flame's global relay here Wednesday amid worldwide condemnation of China's crackdown in Tibet and its human rights record ahead of the summer games in Beijing." it is not totally uncalled for.
I do not mean to imply that Americans are being restricted in their ability to protest. The mere fact that Breitbart is reporting that so many cops will be out for the torch run is attestation to the impact the global protests have had. However, at times protesting is not enough. Studies show that unless significant monetary or physical (i.e. violent) pressure is exerted, governments will more often than not simply ignore protests.
Of course, the journalistic outcry will impact China's leaders and force them to recognize that they do not operate in a bubble. Be that as it may, I am dubious of the lasting effects this brief outcry will have on impacting significant policy change. Witness Darfur.