although the president doesn't really run the country in the way that our president does, i find this whole race to be completely fascinating. if nothing else, just watching how iranian society is reacting to the race, and watching the west not react.
as for predictions, i predict a run-off. there don't seem to be any official polls, but a bunch of people have been talking about a moussavi surge that may deliver him an outright majority. but i've seen enough union elections (where there also are no polls) to know that this fuzzy "sense of a surge" is often completely wrong. people tend to talk with people who are voting the way they want to vote. without a scientific poll, your perspective on any pre-election situation is always going to be skewed in favor of what you want to happen. plus, this is a four-way race. while it's pretty clear that moussavi will get the bulk of the anti-ahmadinejad vote, that vote will still be split with two other candidates. it would have to be a total blowout for anyone to get over 50% in the first round.