For those that missed Hank's Letterman appearance, Hank told a story about Hawking coming to the studio to do the voicework read through for last nights episode. He was late, really late... 10 minutes turned into twenty, twenty minutes into an hour. People were pissed. Then, as they were about to go ahead without him, Harry Shearer looks up from his script and says: "Does the man have no concept of time."
Funniest. Story. Ever.