It’s official: David Wu has resigned from his position. It took affect yesterday at the end of the day, making him the fourth member of Congress to resign this year in the wake of a sex scandal.  The 56 year old had announced his intention to resign after the debt ceiling crisis was over.  The Oregonian published allegations that he had an unwanted sexual encounter with an 18 year old woman.  Wu has told his staff that his actions were consensual, but he opted to resign after House Democratic Leader Nancy Pelosi requested an ethics probe.