One more thought on the possibility of revolution in Tehran. The key thing to note is that Iran today doesn't at all resemble Iran in 1979. During the last days of the Shah, his army was facing defections of over 1,000 a day, according to Ken Pollack. Khamane'i's security forces today suffer no such thing. Back in December of 1978, meanwhile, the demonstrations had grown to over 9 million people. The 2002-2003 protests in Iran, meanwhile, amounted to no more than a couple thousand students. Most importantly, though, the Shah abdicated in 1979 because he refused to crack down hard on the Iranian protestors. Khamane'i and the hardliners are considerably more ruthless. So while I'd rather not be pessimistic, all signs point that way for now.