Al Jazeera reports: Thousands of people descended on Tahrir Square to protest on Saturday night, a spontaneous outpouring of anger after a Cairo court sentenced former president Hosni Mubarak to life in prison but acquitted a number of other former regime officials.

The verdict was initially met with euphoria: Egyptians celebrated upon hearing that Mubarak was convicted of complicity in the murder of more than 800 protesters during the Egyptian revolution in January of 2011. It was the first time an Arab head of state had been convicted, and a major accomplishment for the revolution which toppled Mubarak nearly 18 months ago.

But the joy was short-lived. Mubarak’s two sons, Gamal and Alaa, were acquitted of corruption charges, and several senior security officials were found not guilty of murder. Some had wanted Mubarak to face the death penalty; others appreciated the verdict, but expected it would be overturned on appeal.

So they flocked to Tahrir Square, the heart of last year’s revolution, to voice their frustration, not just with the verdict but with Egypt’s post-revolution military leadership.

“It’s garbage,” Najdi Mohamed el-Din said of the verdict. “And it has made us realize something. The revolution of January 2011? We need to do it again, and we need to do it until everyone who was with Mubarak is gone.”

More than 5,000 people had gathered in Tahrir before midnight, and some planned to spend the night. The atmosphere felt almost nostalgic, as if protesters were reliving their roles from last year’s revolution. Many vowed not to leave the square until their demands were met.

Yet they struggled to articulate what, exactly, those demands were, and there were moments of disunity inside the square. At one point, the April 6 youth movement tried to hoist its flag; other protesters demanded they lower it. An hour later, a heated argument among another group ended with several men beating each other with folding chairs.

Several prominent politicians visited the square on Saturday night. Hamdeen Sabahi, the defeated leftist presidential candidate, was the first to appear, to an energetic welcome. “You are the president in our hearts,” some protesters chanted. Abdel Moneim Aboul Fotouh, the moderate Islamist candidate who placed fourth in last month’s presidential election, also made an appearance.

So did Mohammed Morsi, the Muslim Brotherhood’s candidate and one of two contenders in the runoff election later this month. In a press conference before his visit, he tried to present himself as the revolutionary candidate. “There will be no fair elections, no fair trials, unless the revolution continues,” he said.

Yet his newfound praise for the revolution – the Brotherhood has historically kept its distance from the protests in Tahrir – failed to win him much support from the crowd in Tahrir. “The Brotherhood is coming?” one man asked sarcastically. “Where have they been?”