A friend of mine made the following comment: "Obama wins 52.9% of popular vote, CNN calls it a resounding victory. Ahmadinejad wins 62.6% of popular vote, CNN portrays scattered opposition protests as a revolution."
There is a point to be made in that the US media are sometimes reluctant to question those in power in the US, and that has lead to an imbalance in scrutiny. A better example would be the elections of 2004; the famous differences between exit polls and official ballot counts cast a shadow over both the US and Ukrainian presidential elections. The difference?
US media by and large buried the story of irregularities within the US election; the very same indicators, however, were taken as proof positive of fraud in the Ukraine. What we saw happen in the Ukraine was a national re-vote under intense scrutiny from international and domestic observers - and that's what we should see happen every time we see significant irregularities whose magnitude is large enough to potentially change the election.
In the case of the Iranian election just past, I think the allegations of massive fraud in reporting the results deserve investigation; the Huffington Post has been assembling everything they can. What I find particularly striking is that all the international media, from Al-Arabiya to ZDF - not just, in other words, US media - are finding their ability to report in Iran sharply curtailed. I do not expect the current Iranian government to conduct a revote; Iran, like the United States in 2004, is a nation with a proud incumbent government willing to hold itself aloof from the wishes of the rest of the world, with little interest in transparency and accountability.
I'm pretty sure elections are stolen on a regular basis, all around the world. There's certainly fraud and voter suppression in every US presidential election, and it has probably changed the result of our presidential elections a half dozen times or more; I hate to think of how many state and local elections are decided fraudulently. And for that reason, whenever there's probable cause to question the results of an election, a full investigation - followed by a recount and a revote - is the right thing to do.