REST was in the original HTTP spec. Most people were just doing it wrong the entire time until recently when it became trendy to go back to the root REST ideals. And by most people I mean everyone involved in SOAP and RPC and other nonsense like that.
No, it wasn't. Fielding's dissertation, in which REST was defined, argues that a certain set of principles were an underlying foundation of the structure of the WWW architecture in its original construction, proposes REST as a formalization of and update to those principles, and proposes further that updates to the WWW architecture should be reviewed for compliance to the REST architecture. [1]
So REST is a further elaboration of a set of principles inferred from the original HTTP spec, not something present as such in the original HTTP spec.
