The light-hearted pillowfights, which the website says were initiated by the decentralised " urban playground movement", aim to turn cities into "urban living rooms" where public spaces can be reclaimed for social and spontaneous use.
While Flash mobs -- sudden, unexpected and short-lived gatherings of members of the public, organized by Web sites and text messages -- usually tend towards the surreal (zombie mobs in Toronto, pillowfights in Buenos Aires) they have also been utilized by pressure groups.