[mercurialohearn]

I'm veering dangerously away from the topic with this, but according to Henry Hitchings, "'Reveal' has been used as a noun since the 16th century. Even in its narrow broadcasting context, as a term for the final revelation at the end of a show, it has been around since the 1950s."

http://opinionator.blogs.nytimes.com/author/henry-hitchings/

http://en.wikipedia.org/wiki/Henry_Hitchings

Just thought I'd throw my two cents in on that, since the history of English is a particular interest of mine.