IN THE LOOP is one of the smartest, funniest films I've seen in a while. It's like THE OFFICE, if the office in question was the state department when declaring war on Iraq. Perhaps the funniest line I've heard in a movie in ages was "Difficult, difficult, lemon, difficult." I don't think I'm ruining it for you, either, that's how funny it is.
The cast is excellent, but the script is what shines, and that's why it got a dark horse nomination for the Oscar. It's about as far from the typical nominee as you could imagine, it's a British film shot on video in the mock documentary style. I do wonder how much was improvised. I don't think it will win the Oscar, but the hopefully the nomination will draw in more viewers. A very funny movie. I almost hope for a sequel.