One heuristic principle states that laughter might be a physiological reaction to novel connections made by assembling neurons in the brain in unexpected ways. I always advise people, in any kind of research or ideation related environments to give special attention to ideas that make them laugh, as there may be more there than "silly".
I saw last night Avatar at IMAX. First 5 minutes: everybody around me (and me included) was seriously (and incontrolablly) giggling as they were accomodating to the new type of viewing experience. Q.E.D.
PS: as i told this story to two people this morning, they laughed. This is how it got turned into a post :)