Fallows, who knows more about Burma and China than most, wrote in his PostGlobal piece on the idea of an Olympic boycott over Burma:

I am constantly amazed, and I think most Americans here feel the same, by how little overt anti-Americanism I encounter in China. (Japanese expats here might tell a different story.) But those who were here when the U.S. bombed the Chinese embassy in Belgrade say that the rage against Americans then was physically frightening. All at once the mood turned angrily hostile. (I have not met anyone in China who thinks that bombing was an “accident.”) The potential for nationalistic reaction against “disrespect” toward China is great. Again, the point: the prevailing outlook by average Chinese toward Americans seems positive, and about the only thing that could change it would be something perceived as a slap at national dignity.

This makes a lot of sense.  It makes even more sense when you consider that Chinese nationalism is already probably going to be rising as the Olympics approach.  This has happened before at previous Olympic Games, the most infamous of which was actually the first Olympiad held in Athens, which was followed shortly afterwards by a reckless irredentist war on behalf of the Cretans that Greece lost.  More to the point, an American boycott of the Beijing Olympics would be exactly as effective as the boycott against the ’80 Games was, which is to say not at all, and would have even less of a justification. 

Boycotting the Moscow Games was meaningless moral preening in the wake of the invasion of Afghanistan, a perfect example of the futility of U.S. foreign policy under Carter, but at least you could understand it as a protest.  It’s not at all clear what message a boycott sends this time.  It will amount to saying: “Hey, China, we know that you can’t fully control this military dictatorship in Burma, but we’re going to punish you anyway to feel better about ourselves!”  Indeed, that’s usually all boycotts and sanctions are ever good for–the self-satisfaction of having made a gesture.  In the real world, they usually either provoke the target regime to worse behaviour or exacerbate poor material conditions for the people. 

We saw how irrationally our own people behaved when allies refused to join in an aggressive invasion of another country–imagine how we would respond nowadays if someone boycotted an Olympics hosted here, and then cube that.  That gives you an idea of how foolish and counterproductive a boycott would be.