From the New York Times:
Osama bin Laden has been killed, a United States official said Sunday night. President Obama is expected to make an announcement on Sunday night, almost 10 years after the September 11 attacks on the World Trade Center and the Pentagon.
UPDATE 12: CNN reports that the operation, conducted by Navy SEALs, took 40 minutes and was initiated by helicopter. The compound was 8x larger than other homes in the area, has 12-18 foot tall fortified walls with barbed wire, and had "extraordinary" security measures.
UPDATE 11: Special thanks to Diogenes2008 for this YouTube video of President Barack Obama's speech announcing the killing of bin Laden.
UPDATE 10: Trying to find updates to make this a respectable diary, but everything is redundant at this point. Here's a snippet from a CNN story:
[...] U.S. officials had received specific information about where bin Laden may have been hiding in Pakistan, according to President Barack Obama.
On Sunday, the president said he ordered an operation -- carried out by a handful of U.S. troops -- to kill bin Laden in Pakistan. They did so after a firefight, bringing out the al Qaeda leader's body with them after their mission was complete.
"His demise should be welcomed by all who believe in peace and human dignity," Obama said in a speech announcing bin Laden's death. "Justice has been done."
UPDATE 9: Paraphrasing again from a statement read on CNN released by former Pres. George W Bush: "Earlier this evening President Obama called to inform me that US forces killed Osama bin Laden [...] I congratulated him and all military personnel involved in this operation and missions all around the world."
UPDATE 8: President Barack Obama personally authorized the operation last week, and the operation took place today. Obama: "This is a moment of national unity."
UPDATE 7: Obama (paraphrasing because I can't keep up with him): He directed forces to take action in Osama's Pakistani compound. Forces found him and had a firefight in which Osama bin Laden was killed. No American forces were harmed in the operation.
UPDATE 6: Obama speaking now:
Tonight, I can report to the American people and the world, that the United States has conducted a military operation that killed Osama bin Laden [...]
UPDATE 5: A crowd has formed outside the White House chanting "USA! USA! USA!"
UPDATE 4: CNN reporting that Osama bin Laden was killed in a mansion outside the Pakistani capital of Islamabad.
UPDATE 3: Numerous US installations in the US and around the world are on high alert in preparation for possible retaliatory attacks. CNN reports that "actionable reports" let to the killing via US assets (drone, etc.). special US forces on the ground.
UPDATE 2: CNN reports Osama bin Laden has been killed, and the United States is in possession of his body. Obama to speak shortly.
UPDATE: CNN says it's going to be about national security.