This is reminiscent of an event that occured in 1970, when Soviet-Jewish dissidents Edvard Kuznetsov and Mark Dimshits attempted to hijack a plane out of Leningrad with 14 other refusniks (two of whom were not Jewish), hoping to get to the West. The plan failed and all 16 were arrested on the tarmac. Kuznetsov and Dimshits were charged with treason and sentenced to death. After significant international protest, their sentences were commuted to 15 years. Everyone else involved in the hijack also served time. Kuznetsov and Dimshits were traded for some Soviet spies in the late 70s.

In spite of appearances to the contrary, the Soviets were very concerned about their image abroad, hence the success of the protests. So, what do you do with a clerical dicatorship that, one, ostensibly doesn't give a shit about the outside world, and, two, is appeased more often than not? Would some international protestation do any good?

I don't think that success of protests such as the campaign to free Akbar Ganji can be attributed solely to the Iranian people.  The dissident movement repeatedly asks for international moral support (as opposed to intervention).  They must do so, as far as I can tell, because they believe it contributes to their efforts.  In a country with an unstable, unpopular regime, the thought that the rest of the world is on your side I should think would make a considerable difference to how you approach your day.  Considering the celebrity status and influence of a man like Ganji, I should think the regime would very much like to be rid of him; but he triumphs because pressure from its own people and from the world community does apparently have some impact.

Iran's regime IS sensitive to public opinion in the Arab world, if not the west. Being that they actively are intervening in Iraq and Lebanon (and increasingly Palestine), their motives will come into question if they mistreat Arabs in their own country (or, more to the point, if word gets out about such mistreatment.)