Let's take a moment to compare and contrast.
Many Americans fully believe that George W. Bush actually lost the 2000 presidential election, or won it by foul means rather than fair. Similar accusations, though perhaps on a wider scale, have been leveled at Mahmoud Ahmadinejad relating to the recently completed presidential election in Iran.
Let's take a look back at 2000:
At every stage of the proceedings there were demonstrations on both sides both large and small. At no point was there widespread outages of cell phone or text messaging service, nor were there riot police making mass arrests, nor was Al Gore held in "protective custody" until it all blew over. Perhaps most pointedly, nobody actually died protesting the election outcome (so far as I know).
All that stands in rather stark contrast to the ongoing situation in Iran. It's patently obvious to any observer, and it must be just as plainly obvious to anyone on either side in Iran that the current government lacks a basic level of legitimacy that even Bush had achieved in January of 2001. It doesn't even matter at this point if Ahmadinejad's election tally is as correct as he claims. A government of, by and for the people should not need mass arrests, tear gas and riot police to keep it in power. That's as true for Iran as it once was for Vietnam.
The Washington Post once editorialized: "[South Vietnamese] President Thieu says he'll quit if he doesn't get more than 50% of the vote. In a democracy, that's not called quitting." They were (and are) absolutely right, but the fact Thieu actually said that out loud says far more about the legitimacy of his government. But Thieu at least had the fig leaf of trying to resist a guerilla campaign staged and funded by the neighboring state (North Vietnam). Iran's borders are secure (indeed, Iran has been accused of attempting to destabilize its neighbor Iraq in recent months). The only possible threat to Ahmadinejad is his own people. You can't say such a thing when describing a democratically elected government and still be making any sense.