Osama bin Laden will turn 50 this year. But, when we picture him today, most Westerners imagine a man who, addled physically by disease and psychologically by the repeated blows the United States has dealt his cause, looks much older than his age: a gaunt figure limping from cave to cave along the Afghanistan-Pakistan border, one step ahead of U.S. forces -- surrounded, perhaps, by a small group of loyalists but cut off from the rest of the world, his… more