Yup, it's the new frontier search rich media transcripts with Google. The content, sadly, is mainly television and not e.g. scripts of movies. I was gunning for a "The Usual Suspects" reference with my search, since the line "Elvis has left the building is used in that film (by Stephen Baldwin). Right now it seems the results are mainly useful for Johnny Carson obituaries.
Actually I don't think Google got here first - Yahoo got it in December. And Yahoo has cool RSS media feed content submission.