Protesters' achievements have been limited
On the eve of last year's May Day demonstrations, Prime Minister Tony Blair dismissed the protesters' cause as "spurious".
By the time he came round to addressing his party conference less than six months later, he had rather changed his mind.
"If globalisation works only for the benefit of the few, then it will fail and will deserve to fail."
The conciliatory tone was the closest the prime minister is ever likely to come to admitting that the stock of anti-capitalism may be on the rise.
Activists' challenge
From Seattle to Genoa to London itself, the institutions and cheerleaders of the world's dominant economic system are being challenged by a small but extremely motivated core of activists.
And, revealingly, these mighty institutions and leaders have decided that ignoring their opponents is no longer an option.
The achievements of the protesters have so far been limited: capitalism hardly looks like it is on the brink of collapse.
But it is also true that, while ten years ago academics were talking triumphantly about liberal democracy and capitalism representing the "end of history", in 2002 the term "anti-capitalism" has become not only part of the political vocabulary but also the public consciousness.
Supporters of a system which in recent times might have been accused of taking its legitimacy for granted are being confronted with awkward questions, about poverty, about third world debt, and about ever-increasing disparities between the world's richest people and its poorest.
On the agenda
May Day protests have stamped these questions on the national agenda.
Although 1 May - International Workers' Day - has traditionally been celebrated with a conventional march on Trafalgar Square, the past couple of years have seen protesters change tactics.
With a distrust of centralised authority and inspired by the anti-roads protests, the new protests have succeeded in drawing attention to various complaints and causes.
Violent thugs?
But it has also made it easier for the actions of a small violent minority to be used to portray all protesters as violent thugs.
As a result activists have become deeply suspicious of the mainstream media.
Websites such as Indymedia and Schnews have emerged claiming to offer activists "grassroots, non-corporate, non-commercial coverage of important social and political issues".
The violence, and coverage of it, distracts attention from the fact that protesters have managed to bring together and organise around what were once treated as isolated, disconnected issues.
A vast multitude of once disparate causes - from anti-monarchy to employment rights to cutting third world debt to the legalisation of cannabis to supporting public services to defending animal rights - are linked.