Hey, did you know that today is the 32nd anniversary of the victory of the Khomeini forces in Iran? It is celebrated there as the national holiday Islamic Revolution Victory Day, Iran's un-Fourth-of-July.
If you follow the timeline of the revolution in Iran, you will see the following sequence of cascading events: huge demonstrations in late 1978, the Shah appoints Bakhtiar Prime Minister on January 3 of 1979, the Shah flees the country on January 16, Khomeini returns February 1 and affirms Bakhtiar as PM on February 4, Khomeini tells his followers on February 10 to ignore a Bakhtiar-imposed curfew and pandemonium follows, and on February 11 the regime collapses and Bakhtiar flees.
One very large difference between Egypt and Iran is that Iran had a ready-made and extraordinarily popular charismatic figure in Khomeini. Egypt seems to lack a similar figure---so far.