Usually it's a magic-based world with either dwarf's or humans introducing tech at an alarming rate. I always think of it like roman empire tech but with guns and steam-powered robots thrown in.
I belive it is the best possible rp setting but it usually crumples if the GM or players are not careful. Now that I think about it, if enough people vote steampunk i'll change my vote to that if it's allowed a 2nd time.