Andrew Sullivan— who I usually have no use for, but who has had excellent coverage of Iran—suggests that what’s going on is in part a struggle over the nature of Islam itself:

(Apparently some of the protesters are carrying the Koran)

The use of the Koran in resisting oppression of this kind, now confirmed all over the place, strikes me as a vital gesture. It puts the lie to the idea that Islam is not, at its core, a religion of peace, however hijacked by the fundamentalists and fascists. It is of a part with the color green and the cries into the night of Allah O Akbar. In this pitched battle, there is also a struggle for the soul of Islam. It is so so heartening to see decent people fighting back to reclaim their faith. Without these Muslims, the world will know no peace.