I have very little to add to the excellent commentary posted by my colleagues Sarah and Haroon about the overblown fear of an Islamist (sorry, Haroon, I agree with Aziz) takeover. However, I did want to add some visual commentary.
The Guardian has a slideshow of the protests. In slide 18, you see men and women praying side-by-side, definitely not in any definition of Islamist government. In other words, the people are ahead of the state and the religious opposition.
Second, the nominal head of the opposition now is Mohamed ElBaradei, former head of the IAEA. When he returned to Egypt to lead the opposition to Mubarak, photos were leaked of his daughter in a swimsuit. The speculation was that the Mubarak regime was trying to drive a wedge between ElBaradei and the Muslim Brotherhood. It seems to have worked, so that ElBaradei can operate free of the restraints of the MB now.
Have no fear, the Brotherhood is not here.