Anti-Mubarak Protesters Gather In Tahrir Square For "Day Of Departure" Demonstration

CAIRO, EGYPT - FEBRUARY 04: Anti-government protesters hold a sign referencing the Facebook social networking website that has been important in organizing protesters in Tahrir Square February 4, 2011 in Cairo, Egypt. Clashes between anti- and pro-government factions in Egypt's central square quieted February 4, as anti-government protesters called for a "Day of Depature" and renewed demands for Egyptian President Hosni Mubarak to step down. (Photo by Chris Hondros/Getty Images)