The French revolution lasted 10 years (1789-99) and was a period of radical upheaval in the French and European history that brought major social and political changes including the collapse of the French monarchy. Compare this with what happened in Egypt where the protests lasted a little over 2 weeks and resulted in the eviction of Mubarak.
Most revolutions are started by unhappy citizens. What shape they take after that and how long they last depends on several factors including of course the mode of communication to organize mass protests.
In recent times, the internet has emerged as a powerful platform for communication and social media has helped accelerate the speed of communication. Realizing the potential damage that could be caused by the internet, the Egyptian government shut down all access to the Internet on the first day of protests (in addition to blocking phone calls).
The revolution in Egypt was just waiting to happen and was of course influenced by the uprising in Tunisia. The revolution may have led to the same outcome even without the internet and social media. However, social media has become an integral part of our communication and definitely accelerated the process.
Long live Social Media!