Joe Wilson lied to the nation, when, in the State of the Union, he called the President of the United States, a liar. In as much as you are part of the class defined as the nation, he lied to you. Beyond that one, I am not a constituent, and therefore don't follow him closely. In fact, outside of that comment, I don't know anything he has said.
Barack Obama has lied, therefore he is a liar. Was what Joe Wilson did disrespectful? Absolutely. A lie? Not exactly. In addition, stephkyle said he lied to his state, which suggests something beyond that action anyways.