What is going on in Iran is not a blank slate that the U.S. can write its own wishes and desires on. Mousavi, the reformist candidate, had the approval of the clerics who run Iran. Many of those who are protesting look to be hoping that Mousavi can recapture the spirit of the revolution of 1979. Mousavi supporters, in other words, are not agitating for Western style secular democracy but they demanding that Iran return, or perhaps newly embrace, a certain form of Islamic Republicanism. Of course, the forces unleashed by these events might cause events to go further than Mousavi supporters ever imagined.
Since this a debate of the direction of Iran's particular version of Islamic Republicanism then the U.S. should stay out of these events as much as possible. Over the past 60 years the U.S. and the U.K. have intervened in Iranian affairs. The results have not been prodeuctive for eith side. The U.S. endorsed a coup of a democratically elected governments and tolerated torture from the Shah's secret police. History seems to indicate that the U.S. should stay out of Iranian affairs. President Obama appears to get this and is acting in a wise manner, and I hope he continues to do so.