Right now Bin Laden is operationally impotent. AQ and the franchises are well aware of that. As was mentioned, he IS still an ideological figurehead. Keeping him out of the public eye, whether by killing him or trying him, harms him more than us. He can make all the speeches he wants, but he's basically old news to anyone in the terror guy chain of command. Bin Laden didn't plan the 9/11 attacks, anyway. He was "chief of state", giving approvals and encouragement - but the actual planner is dead. He still says "Yea, Verily" on occassion to keep the masses pumped - but can't do much else. He can and does give general strategic direction, but their strategy is pretty easy. Any number of several could do it. To kill him now, by that I mean a full court press to go after him, would do much more harm than good in the overall scheme of things.