President Mubarak was caught off-guard. Who knew that people were so dissatisfied in Egypt? Probably a lot of people in Egypt, since so many of them are so forcefully demonstrating even as Mubarak promises to step down.
The Egypt situation is new to us, but it's on old story: leader assumes he will be in power perpetually but then circumstances shift, dissatisfaction grows and a revolution breaks out. Revolutions are not common, but there have been a lot of them throughout history. What's new about this one?
The Internet, and mobile communication tools.
How much longer would it have taken for the anti-Mubarak populace to organize opposition if they had not had these tools? And how much quicker did their hostility grow when Mubarak shut down Internet service in Egypt? We can't know for sure, but it's not unreasonable to conclude that the Internet's presence (and its removal by Mubarak) played an integral role in the revolution's arc.
Arab regimes are renowned for their strong social controls. The Internet is quite the fly in that punchbowl. But, alas, it's too late to yank the Internet. Why is shutting down the Internet worse than imposing Marshal law, or other more overt and menacing forms of governmental control?
If you're the leader of a country that is likely to face an uprising you might want to study up on that, and see if you can answer that question intelligently. Of course, that won't happen. The old thing that leads to revolutions (arrogance) never can see how a new thing will challenge “supreme power.”
I wonder which arrogant ruler will next try to shut down the Internet?