"The Muslim Brotherhood Will Rule Egypt."
No. While the Islamist movement is without question Egypt's most organized opposition movement at the moment, it has said explicitly and repeatedly that it does not seek the presidency. For now, the Muslim Brotherhood has swung its support behind retired International Atomic Energy Agency chief Mohamed ElBaradei, a secular liberal who played a key role in catalyzing the protests. It's not clear whether ElBaradei seeks the presidency himself, though he has said he will run if asked.
As for the Muslim Brotherhood itself, it probably represents no more than 20 percent of the Egyptian population. And now that the mass public has been mobilized and energized by calls for freedom and good governance -- not Islam -- the movement is in danger of being pushed to the margins of political life. Egyptians are a religious people, but most evince little desire to be ruled by Quranic diktats.
To be sure, the Muslim Brotherhood can put a lot of bodies on the streets, especially in strongholds like Alexandria or in cities in the Nile Delta. But it's worth noting that the group did not officially endorse the initial round of protests. (One Brotherhood leader, Essam el-Erian, even said, "On that day we should all be celebrating together" instead of protesting against the police.) Yes, its youth wing later played an important role in defending the barricades in Tahrir Square, while its networks outside the square were critical in bringing in supplies to sustain the protests. But it's not clear how loyal they are to an older leadership that failed to squarely confront Mubarak for decades. A broad, secular youth coalition, branding itself as the true custodians of the revolution, would have enormous appeal at the ballot box, even for young Brotherhood supporters, many Egyptians told me.