The media one, that is. I managed to write a column on this question while blogging. It's at the Sunday Times here. Money quote on Twitter:
The misspelling, the range of punctuation, the immediacy: it was like overhearing snatches of discourse from police radio. Or it was like reading a million little telegram messages being beamed out like an SOS to the world. Within seconds I could transcribe and broadcast them to hundreds of thousands more.
As I did so, it was impossible not to feel connected to the people on the streets, especially the younger generation, with their blogs and tweets and Facebook messages all instantly familiar to westerners in a way that would have been unthinkable a decade or so ago. This new medium ripped the veil off “the other” and we began to see them as ourselves.
All the accumulated suspicion and fear and alienation from three decades of hostility between Iran and America seemed to slip away. Whatever happens, the ability of this new media to bring people together - to bring the entire world into this revolution on the streets of Iran - has already changed things dramatically.