Representative Joe Wilson of South Carolina was seemingly on a personal quest to make Republicans look bad last night during the president's speech. He actually yelled, "you lie!" in response to one of Obama's points. Wilson has been in Congress for eight years. You'd think in all that time he would have learned how presidential addresses to joint Congressional sessions work.
Whenever a president, any president, addresses Congress, much of his speech will at least arguably be full of lies. Aside from being rude,disruptive and disrespectful, it's just not reasonable to have members of Congress yell back at the president every time he says something they think is a lie. There are enough delays as it is. Here's how it works. The president gets to say whatever he wants. If the opposition disagrees with something they sit there silently, refuse to applaud, or at worst sort of moan or rumble quietly in disagreement. Then they get to give their own televised response anyway. That's when you counter the president's lies and put your own spin on things.
Wilson recognizes that he behaved badly and has apologized. Hopefully in the future, members of Congress will remember to act with respect toward the president in such a formal occasion.