It may sound crazy, but thank God it happened the way it did. The UN coming together to fight terrorism is one of the best things that ever happened to the world IMO.
You know there were voices in some countries after the attacks calling for 'throwing out the rule book' 'taking the gloves off', you know all the usual euphemisms for illegal action, IMO it could have happened if it wasn't for the way the UN took charge of the counter-terrorism campaign.
The quick decision to launch a police and intelligence led campaign against the terrorists brought the world together as never before. The US troops who captured Osama bin Laden in the tribal areas of Pakistan were of course needed in that lawless part of the world, but the unprecedented police and undercover cooperation that pin-pointed his location was what led them to his position. Imagine the disasterous implications if the world's militaries had been the lead agencies? They'd probably still be blundering around. Bin Laden might even still be free.

Doesn't bear thinking about.
Who can forget the UN secretary general's TV appearances? First after the attack, when his words reminded us that we were "one world, one people, one purpose - to live in peace and free from terror." and second when he announced the capture of Bin Laden, the magnanimity of his offer to address the 'jihadists' grievances, the dignity and open mindedness in promising reconciliation.
I'm personally delighted that the UN has 'grown up' as an organisation and now looks more and more like the 'world government' it was supposed to be when it was created.