Well for American political satire the two biggest players would be The Daily Show and The Colbert Report. Saturday Night Live does the occasional satire skit on American politics which usually ramps up during presidential elections. Movie wise there is a shortage of political satire. Thank You for Smoking, starring Aaron Eckhart, i think can be seen as a satirical movie. A classic would obviously be Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb directed by Stanley Kubrick. Not movie but The Onion does the American political satire: http://www.theonion.com/section/politics/ then again its not a movie I'm not sure how you feel about that. For Dr. Strangelove it basically makes fun of the nuclear/Communist scares during the Cold War. Other than these two I can't seem to think of anymore. Here are some links:
Thank You for Smoking