I don't think they would risk a Miller's Crossing situation, with the guy who is supposed to be dead popping up inconveniently. Thus, we can conclude that he is dead, and died within the last ten years. The last real evidence of his being alive is interviews in the fall of 2001 (see here and here). Later videos and interview transcripts are obviously bogus intelligence creations.
There is no way to know when he died.
The timing is odd from an American political point of view. Why not wait until just before the Presidential election? If the killing was phony, and Osama was already dead, they could have staged it any time. If the killing was real, Osama obviously wasn't going anywhere, so they could have delayed the operation.
The most obvious reason for the timing is the talk about the withdrawal of American troops from Afghanistan and Iraq. A good way to stop this is to ratchet up the War On Terror by staging a false-flag attack against the United States characterized as 'al Qaeda' revenge for the death of Osama bin Laden. Americans are already being brainwashed for this attack.
"Bin Laden's great escape: How the world's most wanted man made fools of elite troops who'd trapped him in his mountain lair" A whitewash of the time the Americans allowed Pakistan to rescue bin Laden, published just a day before the 'death' announcement.
"He said he was going to die a martyr's death for Allah and Islam." (from the Hamid Mir interview)
Harrison Ford - A hypothetical question: if Harrison Ford were to convert to Islam would he still be allowed to fly planes at the age of 74?
48 minutes ago