When the iranian president spoke at Colombia Univ. he extended an invitation for the Bush administration to speak at iranian colleges. I wouldn't expect president Bush to go but it would be a good idea if he sent a representative like secretary of state Rice or other higher ups.
The majority of iranians are strongly dissatisfied with the current regime and speaking at a college would be great diplomacy and possibly drive a bigger wedge between the regime and the people.
Unfortunately things like villifying Ahmadinejad, labeling the iranian army a terrorist organization, and these hypotheticals of how we would deal with a nuclear iran has us on the road to war with iran. I feel that the moment the american military would step foot in iran all the people who are against iran's regime and hate Ahmadinejad would become nationalists and fight against us.