ADDED: Here's a nicely detailed obit. Excerpt:
Mr. Wallace was a master of the skeptical follow-up question, coaxing his prey with a "forgive me, but…" or a simple, "come on."...
His late colleague Harry Reasoner once said, "There is one thing that Mike can do better than anybody else: With an angelic smile, he can ask a question that would get anyone else smashed in the face."
Mr. Wallace said he didn't think he had an unfair advantage over his interview subjects: "The person I'm interviewing has not been subpoenaed. He's in charge of himself, and he lives with his subject matter every day. All I'm armed with is research."