Happened with phones too. I know of at least one riot in NSW, Australia was done with SMS.
'On 12 January 2006, the Sydney Morning Herald reported over 600 people had been arrested for their alleged involvement in the riot or related events. Offences included 1,151 traffic-related, 17 riot-related, two malicious damage by fire and three for sending text messages.' http://www.youtube.com/watch?v=ZDcr6AYUOBc
'On 12 January 2006, the Sydney Morning Herald reported over 600 people had been arrested for their alleged involvement in the riot or related events. Offences included 1,151 traffic-related, 17 riot-related, two malicious damage by fire and three for sending text messages.' http://www.youtube.com/watch?v=ZDcr6AYUOBc