Steampunk is a genre and subculture which, according to Wikipedia, has been around since before I was born. It has only recently come to my attention, but it's done that with a bang.
Steampunk consists of fantasy and science-fiction set in a Victorian-like era. The genre includes books like Joan Aiken's Dido Twite books (Black Hearts in Battersea etc.), Philip Reeve's Mortal Engines and Stewart and Riddell's Edge Chronicals.The work of Jules Verne and H.G. Wells could be considered proto-steampunk - they are, essentially, emulated by steampunk writers, whether intentionally or coincidentally.
I haven't seen any notes on steampunk movies, but I suppose The Golden Compass would fall into that category. There are likely more, which I would recall if I'd watched as many movies as I've read books. Steampunk music and design are also developing, although seem somewhat undefined as yet. Perhaps that means I'm not so late to jump onto the bandwagon after all.