What do talkshow hosts and their guests talk about behind the scenes?

I'm curious to know what exactly are they talking about in that brief moment between the host saying "We'll take a break, We'll be right back." and the camera zooms out and you can see perhaps Conan or Jay Leno reaching in to whisper animatedly into the guest's ear and then the commercials start. Does anyone know what they talk about? Is there any website that talks about this?