Egypt Government decided to ban Twitter.com in Egypt on 25 January due to its role in dissemination of the revolutionary ideology among Egyptians.
Although Facebook has a similar or may be larger role, it have not yet been banned, however some news sources claim that it will be banned during the coming hours.
It worth mentioning that big demonstrations were held in Tahrir square in Cairo and in many other places in Egypt against the government and its policy, that lead to death of 2 civilians in Suez due to tear gas asphyxia and one policeman due to direct head injury with a stone from demonstrators.