I think it's perfectly OK to wear a lapel pin flag if you are attending your country's national day celebration, an astronaut, or under twelve years old.
Obama has the guts to refuse to wear a USA flag-pin. I can't help but respect him more for it. Obama said of his decision not to wear the flag:
You know, the truth is that right after 9/11, I had a pin. Shortly after 9/11, particularly because as we’re talking about the Iraq war, that became a substitute for I think true patriotism, which is speaking out on issues that are of importance to our national security, I decided I won’t wear that pin on my chest.Good on ya Obama.
Photo: Canadian PM Harper is shown greeting French President Sarkozy. In the tradition of George W. Bush, Harper wears his country's flag pinned to his lapel. (h/t: Heart of Bitterness)
French President: Does this man think I do not know he represents Canada?