A few weeks back there was a CNN report that said that there would be retaliation efforts from Al Qaeda if Bin Laden is killed (but that statement was based on early post-911 era). It said that terrorists were able to slip a nuclear bomb of some sort into the US years back.
Let's hope that isn't true! I'm afraid this news would spark a new rage and motivation for terrorists.
BTW I checked the alleged location where he was killed, it seems like it was a highly urbanized area. Makes you wonder if those Pakistanis are really trustworthy or not.