The UN does serve a purpose. it sets a forum where the nations of the world -can- discuss things. It's scope is what failed.
There's too much personal interest and agendas, hardly anything gets done. Because of the asinine UN rules of engagement, this meddlesome pirate situation off the Somali coast hasn't been handled. Can't engage pirates once they've taken a ship, what the frack is that??? Here's a case where the big powers need to take off the kid gloves and do what must be done, and to hell with the UN. Each nation must weigh the risk to its own shipping; if you attack and seize our ships, we're coming in to take them back, at the threat of deadly force if need be. If you kill the crew, we'll bomb Somalia so fracking hard that your children will be reeling from the shockwaves five generations from now. You can't play bunnies and kittens with pirates; bullies only understand one language, they figure it out once someone knocks them on their ass hard.
I'm wary when people say the UN needs some restructuring or a replacement, because about the only thing that would be an effective reforming, would be to make the UN, or it's replacement, a true world government.
You're not thinking wide enough; the only alternative is not a true world government, because no matter who tries to implement that, it's doomed to failure.
I must be blunt; as a species we're still too tribal and underdeveloped...the sort of thing that Star Trek's galactic Federation would quarantine and leave to their own devices. The 'alternative' may need to be power blocs; regional or continental UN's. I believe some times we all need a big 'time out', and get set back in our respective corners of the sandbox with T-shirts that say Doesn't Play Well With Others.
The USA will do as they please and will simply ignore the UN when it comes down to Iraq.
Correction; the USA under a Bush administration will do as it pleases with Iraq, but Bush is gone now. Invading Iraq was about securing resources, plain and simple; any other cause that anyone cites including humanitarian aid and freeing Iraq from a despot is pure collateral effect. The Iron Triangle did not remove Saddam because he was a dirtbag, they did it because he wasn't playing ball with them anymore. Same with Panama.
We can only have faith in Obama that he will work closely with the Iraqi government for a timely withdrawal. Being as the government there has stated prior that they favor Obama's proposed timeline, I'd expect some good results to occur.
Russia should consider a vested interest in US success and withdrawal from Iraq as well, regardless of our differences past and present, as the more troops we don't have there, it removes a major theatre of operations that can shift forces into Afghanistan to utterly crush the taliban, al queda and whoever else we need to take out.
Several decades of our little Cold War has been heating the pot in Asia and now it's boiled over with this 'war on terror', which consists of combatants who bear no love for mother Russia either. This is one situation where our countries should be collaborating, UN or no UN, but there are indeed others...