If the same demonstration were to happen in Iran, the entire US media would have shown the images of the young person who immolated himself. It would take the opportunity to show the unpopularity of the Iranian government, its repressive policies, and its undemocratic tactics.
Unfortunately, the events did not happen in Tehran. They happen in Tunisia and the US media does not want to show Muslim people demonstrating peacefully against the Tunisian President Ben Ali, who, as you might have guessed, is a good friend of the European Union and the US.
To know about the events in Tunisia, one must turn to Al-Jaseera and read one of its report http://english.aljazeera.net/indepth/opinion/2011/01/201113102452251132.html
I say that I prefer Al-Jaseera's report because it does not shy at pointing out Ben Ali's politics of corruption, authoritarianism, and repression