The problem that I have with Iran is not that I view them as a threat to my country (USA) or the Middle East: it is that Iran is the second most despised government in the world (behind #1 Israel, and slightly ahead of #3 North Korea in just about every international opinion poll).
I would expect a more conciliatory approach from a leader of a widely despised government (internal human rights, suppression of free speech, an economy that is so bad that their educated population leaves in great numbers, etc.) I don't think that any rational person really views Iran as a real security threat (although Iran is a convenient political issue in my country), but I have real problems with their internal (to Iran) behavior. Re: nuclear power technology in Iran: as long as they continue to be a member in the IAEA and allow inspections, that is good enough for me, but I understand the arguments of other people who don't feel comfortable with this. Unfortunately, incompetent foreign policy by the Bush administration has certainly given Iran more influence in their part of the world, but that is something that we now have to learn to live with - no taking back mistaken actions and policies, and "doubling down" on the bad bet of attacking Iraq, by attacking Iran, would be a horrible mistake (a long shot neoconservative wager that is a true nightmare scenario for the whole world).
I would like to make a more general point:
The world has become a much safer place over the last several decades, based on fewer civilian deaths and a decreasing general level of violence in the world. Also, compared to the constant threat of nuclear annihilation during the cold war, things are definitely looking good right now: something we should be grateful for.
One reason the world has been progressing into a safer place is globalization and interlocking economies. If it were up to me, looking out for the welfare on my own country (USA) but also caring about all people on this planet, I would have more trade, talk, student exchange programs, tourism, etc. with all countries in the world (OK, I don't really don't want to go on a vacation to North Korea, but you get the general idea). The better the flow of ideas, dialog, tourism, and education abroad programs, the better off the world is, and for that reason I would like to commend Columbia University for inviting Ahmadinejad to speak and answer questions today. Ahmadinejad did not make a good impression on me, but I was still glad to hear him. You can bet money that some politicians will try to make political mileage out of this, but they will be acting out of self interest, not for the general good.