Osama bin Laden was declared dead by the US government on May 1st. A team of elite US soldiers flew to a city 30 miles outside the Pakistani capital, landed in a walled compound that harbored bin Laden, got off the helicopters, found Bin Laden, and shot him in the head.
This is the official version of the story from the US government. However, conspiracy theories have proliferated on the internet.
The main factor fueling them is the lack of proof. (The US government, in its defense, said it can't reveal too much information for national security purposes.)
There is no body of bin Laden (it was buried at sea), no photo, and no video footage from the helmet cam of the Navy SEALs.
There are also those who believe bin Laden was a CIA agent, the US government faked the 9/11 attack, and bin Laden's assassination on May 1st was a hoax.
Below are links to information on various conspiracy theories about bin Laden's death.