ETA: Ben Ali has left, France is refusing him entry, and a whole lot has happened since I submitted this. The source link is a live feed; the situation will keep going for a while yet.
Tunisian President Zine al-Abidine Ben Ali has sacked the government and said new parliamentary elections will be held within six months. Earlier, police fired tear gas to disperse an unprecedented demonstration outside the interior ministry in Tunis, sending people fleeing into surrounding streets.
Sources tell al-Jazeera TV that the Tunisian security forces have arrested members of Trabelsi family at an airport. Many of the protesters have expressed their anger at the power, wealth and influence of the extended family of President Ben Ali's second wife, Leila Trabelsi. "No, no to the Trabelsis who looted the budget," has been a popular slogan. Many refer to the president's relations simply as "The Family" or "The Mafia", according to the New York Times.
Mahmoud Ben Romdhane of the opposition Renewal Movement tells BBC World News: "At this moment, according to the latest information that I have, the president it no longer in power and a coup has happened. If this information is true, the answer is clear. He will no longer have the power to decide to accept or refuse [the demands for him to step down]."
From here, live feed. Includes graphic video.
...Maybe. But regardless Anonymous can now say they had a hand in toppling a government.