The economist had several articles on the riots in Great Britain and one of these, "The Blackberry Riots", discussed the way technology makes it easier for people to protest and/or riot. In particular, they talked about the Blackberry, with its Blackberry Messenger (BBM) that allows one to send messages to one or more people for free.
The article discusses how one British MP has considered suspending BBM. Closer to my home, people have protested the San Francisco BART subway system's decision to disable cellular service within their underground stations. Supposedly, this was done to make it difficult for protesters to coordinate their actions.
Both of these strike me as more whack-a-mole actions than something truly productive. While BBM may provide an easy to use application for coordination, there are plenty of alternatives. Similarly, I don't believe disabling cellular service is actually going to achieve the goals of disrupting protests, maybe initially, but I expect the future to bring ways of handling mesh networks that relay signals between Bluetooth networks to allow routing directly between cell phones instead of the carriers networks.
I don't condone the violence and rioting, but the reaction seems to be naïve. As if we could just get rid of our technology to return to a golden age of peaceful protests.