I would have to say a catogorical and emphatic "No" to any notion of shutting down communications networks or social media streams. That is the thin edge of the wedge and as I recall the UK government voiced their (our) dislike of Egypt's President Mubarak doing just that during the so-called "Arab Spring" this year.

First off, we cannot go criticising the despotic nations and then go and do precisely the same thing ourselves when it suits us.
Nextly, I do not believe that we can actually trust our Police or Government (local or national) to make sane decisions on when to shut off the communications. Witness how out of control the Police get at times, over reacting, shutting down roads and services that they have the powers to. Often with very disruptive and negative consequences. I would be completely loathe to hand over such powers to these people to shut down the telecommunications of whatever means.

I think it is vitally important to note that whilst the perpetrators of the chaos were using various "networks" to communicate across so, too, were the masses of people being affected in one way or another. Yes, there were some idiots out there who were spreading misinformation about the riots. But is any of that good enough reason to close down for the masses? I think not.

No, we must resist at all costs any notion of Police and governments shutting down public networks.