Shane Snow wrote a good column recently on the importance of asking good questions. He argues that asking good questions serves as a crucial leadership capability that people should develop. Snow makes some good recommendations, such as trying to not ask leading questions, reframing questions later in a conversation when you haven't received a complete response, and replaying what you have heard to insure that you have a solid understanding.
I would make a few additional points. A good leader also asks questions that explore a topic a bit deeper, even when they appear to have a consensus in a meeting. A good leader uses those questions to accomplish two things: 1. Test what-if scenarios, and 2. Test for understanding and alignment. With regard to the first point, leaders want to make sure that they uncover any hidden risks. They might ask: "What if some of our assumptions prove to be untrue?" "What if our competitor responds in an unexpected way?" With regard to the second point, a leader needs to make sure that a team is truly on the same page, and that everyone shares a solid understanding of a decision rationale, as well as each person's role and responsibilities during implementation. Asking good questions can help reveal whether people are truly on the same page before moving forward with execution of a plan of action.