Some interesting speculation from Over The Counter Culture today on the use of mobile communications to overcome the ease with which modern police forces can crush demonstrations. So called txtMobs can be used as
"a way of coordinating thousand-strong crowds of protesters to converge with short notice (i.e. short notice to the police) on particular spots; to disperse immediately; to avoid blockades; to track particularly abusive police units; to unmask undercover agents (in this case, a txt/SMS message was sent to everyone to let them know that undercover ops were wearing red and orange bracelets)."
There are a few decisive moments in the history of technology that mark a turning point in the power of the state. Improvements in canon technology (around the time of Henry VIII) so that central government could readily demolish castle walls marked the effective end for the practical independence of feudal lords from the king. Improvements in machine-gun technology (around the middle of C19th) so that a bare handful of police or soldiers could stand indefinitely against any number of civilians marked the effective end of successful rebellions by unarmed urban mobs against determined opposition*.
Similarly, recent improvements in communications, surveillance and logistics technology have made it increasingly trivial for central authorities to control and suppress even peaceful demonstrations. I find it extremely comforting, therefore, to see that improvements in mobile co-ordination have shifted the balance briefly back the other way and made it possible for large groups to assemble without warning, congregate without fear that excessive police response will go unrecorded or unreported, and disperse again without serious fear of detention.
*A lot of the history of the last couple of hundred years has therefore hinged on whether governments ordering soldiers to fire into an unarmed crowd have received a "yes" or a "no".