In Korea, Mr Rheingold told Technopedia, the young cyber-generation used the OhMyNews.com website and text messaging to mastermind a campaign that swung the election in favour of President Roh Moo-hyun. In America, while the Howard Dean presidential campaign has exploited the internet and mobile phones in a grassroots movement, the left-wing activist site moveon.org has turned into a 'formidable' popular cohesive force.

Likewise, the global antiwar protests in the run-up to America's attack on Iraq could never have been organised on such a scale and at such a pace without the self-organising capabilities that websites, weblogs, e-mail and text messaging allow, Mr Rheingold claims.

Also known as a 'flash crowd', the phenomenon he chronicles can be traced back to a 1973 science-fiction short story by Larry Niven. In the story, teleportation is routine and 'flash crowd' means the ghoulish mob that abruptly teleports to places in turmoil.

The original smart mobs were rather more docile teenage 'thumb tribes' in Tokyo and Helsinki who punched out text messages on big basic mobile phones to organise impromptu raves or to shadow their favourite stars. In Tokyo, swarms of teenage fans would miraculously materialise at subway stations where a rock god was said to be heading.

The wider craze seemed to be focused on New York. First, a gang of web mavens was invited by e-mail to take part in an art event in the city, then the first flash mob materialised in Macy's, the department store, when about 100 people arrived and asked for a vast 'love rug' at the main checkout. Two weeks later, another group of 250 people gathered at Grand Central Station. Confronted by a large police presence, they reconvened to the Grand Hyatt hotel and burst into raucous applause for 15 seconds, then melted away the police arrived.

Since then, the movement has been gathering momentum. Now mobs are cropping up everywhere from Texas to London, and the rise of the mob will continue, Mr Rheingold predicts.

'I think these are just the first signs of a large shift in the way people organise social, political, cultural and economic activity. For mobile communications and pervasive computing, I think the current era is equivalent to the early 1980s, when the PC first became available [but people didn't know what to do with them], or the early 1990s, when only engineers used the internet.'

Earlier this month, about 200 people showed up on a Central Park ridge. Once gathered, participants tweeted like birds and crowed like roosters. It all seems more cuckoo than cool, but more fun than the stunts carried out by New York's more established mob.