Words of caution from Fawaz Gerges, a professor at the London School of Economics:
"Yes, Mubarak is out but the political structure remains in place, the economic structure remains in place, the Mubarak regime remains deeply entrenched in place. You have Vice-President Omar Suleiman, the military commanders, the prime minister, the defence minister. Yes, it’s a giant step, it’s a major, major watershed for Egypt and Egyptians - Mubarak has been in power for 30 years - but the reality is the challenges have just begun."
Also, From the BBC’s Paul Danahar in Cairo:
"The atmosphere in Tahrir Square is electric. One man told me he couldn’t believe they’d won. But the big question is, what will winning look like when they wake up tomorrow? The importance of this event cannot be understated but neither can its possible impact on the wider Middle East."
BBC News Liveblog