Yes, imagine that. You cleave off a historically-sensitive part of someone's country, and they get all snippy about it. This is going to be as hillarious as watching the Americans suddenly discover that backing the Shah wasn't the best PR move in history.
I think, long term, the example of Kosovo is going to ruin any possibility of humanitarian intervention for the foreseeable future: we (NATO) explicitly, repeatedly said that the 1999 bombing of Yugoslavia was not a prelude to partitioning of Kosovo. President Clinton himself said it repeatedly, in public. And now it turns out to have all been lies.
You want to try and send peacekeepers in to Darfur with this record behind you? I mean, forget Iraq: the single good example of what western military might do was based as much on lies (claims that hundreds of thousands of Kosovars had been murdered, when nowhere near that number were) as the Iraq War was. And was used to dismember a sovereign state in defiance of international law.
There was a time -- we called it the 90s -- where the UN was able to be somewhat more effective because, despite their reservations, Russia and China sat on their vetoes and didn't stonewall the entire process. I think it's safe to say that time is over, and it's in large part because of our own actions.
The interesting thing here is that peace is being bought by the Europeans. The recent presidential elections in Serbia went to the "right" guy (the one who disavowed violence in Kosovo) largely because of a promise of lots of goodies from the EU -- visa-free travel for Serbs in the EU, plus a whole pile of aid money. The American military snottily talks about how the US "cooks dinner" and the Europeans "do dishes", trying to dismiss the power that Europe has when it comes to peacekeeping and nation-building. But there's a very real case to be made here that we'd be looking at the third Balkans War since 1990 if it weren't for the EU.
I'll have more to say about that in a bit.