“This is it. The big one. This is the first revolution that has been catapulted onto a global stage and transformed by social media,” says Clay Shirky, professor at New York University and author of the book Here Comes Everybody: The Power of Organizing Without Organizations. And what’s had the greatest impact?

“It’s Twitter,” says Shirky.

This isn’t really the first time demonstrations have been organised or teargas reported via Twitter. Try Bangkok in October 2008. Try Chişinău in April 2009. But we are talking about a powerful new political tool. So, as Crikey reported yesterday, the Iranian government tries to block Twitter and other social media sites, just like the Chinese did before the Tiananmen Square anniversary only days before.

Easier said than done.

“Twitter is shareable and open and participatory in a way that Facebook’s model prevents,” Shirky points out. “So far, despite a massive effort, the authorities have found no way to shut it down.”

It’s compulsory at this point to quote Gilmore’s Law: “The Net interprets censorship as damage and routes around it.”

But Twitter is also a powerfully seductive mechanism for immediate emotional engagement — “blogging’s meth-paced spawn,” I’ve called it. First-hand accounts of being teargassed demand an immediate response, and forget the analysis.

“It’s easy to get caught up in the moment, feel the infectious nature of rumour and the thrill of disseminating third(/fourth/fifth/sixth…)-hand experience, and want to feel part of a global movement,” says Meg Pickard, social media specialist at The Guardian.

Never heard of Mahmoud Ahmadinejad or Mir Hossein Mousavi? Who cares! Thanks to Twitter, we’re all instant experts on Iranian electoral politics. The Houston Chronicle’s Corilyn Shropshire is just one of many urging us to “green” our Twitter or Facebook avatars in solidarity with the protesters in Tehran. And people are responding, offering the demonstrators ways round the Iranian government’s blocks.

So why are we supporting Tehran’s green-clad demonstrators, exactly? Is it because they’re English-tweeting middle class city-dwellers with smartphones like us, easier to relate to than the conservative rural Iranians who support Ahmadinejad? Is it knee-jerk support for anyone fighting the man the US neocons portrayed as a new Hitler, even if so far it appears he was elected fairly (at least as such things go)? Or could there be larger forces at play?

Why has the world engaged with tweets from Iran, when there wasn’t the same reaction when they came from Thailand or Moldova? Could it be… 138 billion barrels of oil reserves and counting?

As Meg Pickard says, “Information which spreads quickly, explosively and loudly isn’t necessarily reliable, accurate or helpful.”