Much of the U.S. press seems to be painting the protests in Iran as a genuine, popular uprising against an autocratic, religiously fundamentalist regime.
It's true that the Iranian government is autocratic and religiously fundamentalist. However, it's also true that that government has the support of a large majority of its people, who mostly live in the rural countryside and small towns, and who are, by and large, religiously fundamentalist. While there may have been some voting fraud in some districts, it should come as no surprise that the vast majority of the population supported their current President.
The protesters are largely urban: college students and young urban professionals. While such populations might be typical in the U.S., they are not typical of Iran as a whole; they constitute a small minority of the population there. They're sufficiently atypical of Iran that they're not even well represented by "their" candidate, Mousavi, who is more typical of the Iranian governmental establishment.
The truth is, the protests in Iran are largely the protests of a minority that is being oppressed by a government supported by a large majority of the people there. They are in no way a popular uprising, and absent an externally planned and funded coup, have no chance of significantly affecting the government.