Because he has a choice of which "Saturday Night Live" he wants to do – either the December 10th episode with Alec Baldwin and Shakira or the December 17th broadcast with Jack Black and Neil Young – Howard has spent the last few days talking about how Jack badmouthed him after coming on the show a few years back.
Howard announced that Jack got word of these discussions and was coming in this morning so that the two could clear the air. As background to the controversy, Robin recalled that Howard saw an advanced screening of "School of Rock" before it came out and couldn't stop raving about it.
Robin added that Howard made it a point to have Jack on as a guest and that, when he did, he spent the entire interview praising his work in the film. Howard acknowledged that was what happened and admitted that he wasn't sure last night that he even wanted Jack to come in, seeing as he wouldn't know if he could trust what he was going to say to him.
However, Howard reported that Beth convinced him to hear Jack out, so that was what he decided to do.