I don't think the UN has all the answers, and I do think UN, and particularly the countries making up the Security Council, know all of their past mistakes and responsibilities for not stopping previous genocides and massacres.
The UN is very much in flux right now. As is our world. Nobody has written or agreed a fair policy by which we should conduct ourselves, although there are criteria to be met when intervention is mooted, as with Libya now.
All we have is a room where representatives of 192 countries will talk to each other - that's all the UN is.
Just because there are terrible regimes the world over repressing and murdering their people, it doesn't mean the UN shouldn't be acting now in Libya. But it is setting an example, demonstrating to these regimes that there can be consequences and showing critics it has teeth after all.
The young generation who are valiantly trying to change the shape of the Middle East to a democratic one are watching and seeing the UN as a positive force. I believe this is important. Otherwise these future leaders may not come to that room of 192 nations, sit down and talk with their neighbours.
Meanwhile the dictators of the world are watching Libya.
They may not be overnight democracies, but some autocratic leaders are making unheard-of concessions to their people's demands already, from sacking their prime ministers and cabinets, to setting a date for elections (which UN observers will hold them too) for the first time in decades... (See Yemen, Bahrain, Jordan, Sudan, to name a few).