Update at 10:37 a.m. ET: NBC's Richard Engel says two independent sources have confirmed that Mubarak will step down. In addition, the armed forces supreme council has convened to begin the orderly transition of power, NBC says.
Update at 10:28 a.m. ET: NBC reports that Egyptian President Hosni Mubarak will step down tonight and that vice president Omar Suleiman will take over as president.
Update at 10:23 am ET: Military and ruling party officials say President Hosni Mubarak will meet protesters' demands, the Associated Press reports.
Check the home page for the AP account of this developing story. Mubarak's departure invites more questions: Will protesters accept Suleiman as a temporary leader -- will the mass demonstrations cease? What will this mean for Egypt's long-term stability? Since Suleiman will essentially become a glorified placeholder, who or what will ultimately fill the massive power vacuum in one of the region's most significant powers?
UPDATE: It looks like Vice President Suleiman may be bypassed in favor of a military junta. Could this be a coup?