Vodafone has conceded in an official statement what we more or less sensed since last night:

All mobile operators in Egypt have been instructed to suspend services in selected areas. Under Egyptian legislation the authorities have the right to issue such an order and we are obliged to comply with it. The Egyptian authorities will be clarifying the situation in due course . [Source]

I like that it is preceded by a link on making it easier to use smartphones (in Europe).

Completely sans irony, naturally.