What will Egypt's "March of Millions" accomplish?

Crowd in Egypt
The crowd gathers in Tahrir, or Liberation, Square in Cairo, Egypt, Tuesday, Feb. 1, 2011. More than a quarter-million people flooded into the heart of Cairo Tuesday, filling the city's main square in by far the largest demonstration in a week of unceasing demands for President Hosni Mubarak to leave after nearly 30 years in power.
AP Photo/Tara Todras-Whitehill