Maybe Jay Leno and Jimmy Kimmel were having trouble booking guests for this Thursday, because they're both appearing on the other one's show!
They both came back on the air last week, and have been having a tough time since actors don't want to cross the picket line. The two plan on talking about who's a good guest, and who's a bad guest.
That might not be the best tactic in trying to book people on the show, but I'm sure it'll be funny. Letterman on the other hand, is having no problem booking guests, and has Lucy Liu, Tom Hanks, and Morgan Freeman all this week! Poor Jay and Jimmy.